diff --git a/.gitignore b/.gitignore
index 2e5c8a76..2acb731f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,6 @@
+# That pesky Mac file
+.DS_Store
+
 # Vim Swapfiles
 .*.swp
 .*.swo
diff --git a/.travis.yml b/.travis.yml
index 0ed81b41..0df2d973 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,23 +11,26 @@ jobs:
   include:
   - name: "Minimum install_requires versions"
     install:
-      - pip install numpy~=1.12.0 pandas~=0.24.0 SQLAlchemy~=1.1.18 psycopg2~=2.7.0
-      - pip install pytest==4.4.2 hypothesis==4.50.2 attrs==19.3.0
+      - pip install -r requirements-test.txt
+      - pip install . numpy~=1.12.0 pandas~=0.24.0 SQLAlchemy~=1.1.18 psycopg2~=2.7.0
   - name: "Late 2019 dependencies"
     install:
-      - pip install numpy==1.17.4 pandas==0.24.2 SQLAlchemy==1.2.19 psycopg2==2.8.4
-      - pip install pytest==4.4.2 hypothesis==4.50.2 attrs==19.3.0
+      - pip install -r requirements-test.txt
+      - pip install . numpy==1.17.4 pandas==0.24.2 SQLAlchemy==1.2.19 psycopg2==2.8.4
   - name: "Newest studied dependency versions"
     install:
-      - pip install numpy==1.17.4 pandas~=0.25.3 SQLAlchemy~=1.3.11 psycopg2~=2.8.4
-      - pip install pytest==4.4.2 hypothesis==4.50.2 attrs==19.3.0
+      - pip install -r requirements-test.txt
+      - pip install . numpy==1.17.4 pandas~=0.25.3 SQLAlchemy~=1.3.11 psycopg2~=2.8.4
   - name: "Pure setup.py install"
     install:
+      - pip install -r requirements-test.txt
       - pip install ./
       - pip install psycopg2~=2.8.4
-      - pip install pytest==4.4.2 hypothesis==4.50.2 attrs==19.3.0
       
 # command to run tests
+install:
+  - pip install -r requirements.txt
+  - pip install .
 services:
   - postgresql
 env:
diff --git a/Makefile b/Makefile
index 6d5cb080..2be8e608 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,7 @@
-NOTEBOOK_TESTS=$(addprefix examples/, examples-dplyr-funcs.ipynb case-iris-select.ipynb examples-postgres.ipynb examples-varspec.ipynb)
+NOTEBOOK_TESTS=$(addprefix examples/, \
+		examples-dplyr-funcs.ipynb case-iris-select.ipynb examples-postgres.ipynb examples-varspec.ipynb \
+		examples-siu.ipynb \
+		)
 
 AUTODOC_SCRIPT=docs/generate_autodoc.py
 
@@ -11,7 +14,7 @@ test:
 	pytest --dbs="sqlite,postgresql" siuba/
 
 test-travis:
-	#py.test --nbval $(filter-out %postgres.ipynb, $(NOTEBOOK_TESTS))
+	py.test --nbval-lax $(filter-out %postgres.ipynb, $(NOTEBOOK_TESTS))
 	pytest --dbs="sqlite,postgresql" siuba/
 
 examples/%.ipynb:
diff --git a/examples/case-iris-select.ipynb b/examples/case-iris-select.ipynb
index 085a6dae..5d9c4c1e 100644
--- a/examples/case-iris-select.ipynb
+++ b/examples/case-iris-select.ipynb
@@ -11,6 +11,8 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
+    "> 📢: **This document was used during early development of siuba. See the [select docs](https://siuba.readthedocs.io/en/latest/api_table_core/03_select.html).**\n",
+    "\n",
     "Many different ways of selecting columns from the iris dataset. "
    ]
   },
@@ -23,8 +25,6 @@
     "from siuba import *\n",
     "import pandas as pd\n",
     "\n",
-    "from sklearn import datasets\n",
-    "\n",
     "pd.set_option('max_rows', 5)"
    ]
   },
@@ -34,9 +34,21 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "iris = datasets.load_iris()\n",
-    "df_iris = pd.DataFrame(iris.data, columns = iris.feature_names)\n",
-    "df_iris['species'] = iris.target_names[iris.target]"
+    "## Rather than import the iris data from sklearn, I am just including the\n",
+    "## first 5 rows.\n",
+    "\n",
+    "# from sklearn import datasets\n",
+    "# iris = datasets.load_iris()\n",
+    "# df_iris = pd.DataFrame(iris.data, columns = iris.feature_names)\n",
+    "# df_iris['species'] = iris.target_names[iris.target]\n",
+    "\n",
+    "df_iris = pd.DataFrame({\n",
+    "    'sepal length (cm)': [5.1, 4.9, 4.7, 4.6, 5.0],\n",
+    "    'sepal width (cm)': [3.5, 3.0, 3.2, 3.1, 3.6],\n",
+    "    'petal length (cm)': [1.4, 1.4, 1.3, 1.5, 1.4],\n",
+    "    'petal width (cm)': [0.2, 0.2, 0.2, 0.2, 0.2],\n",
+    "    'species': ['setosa', 'setosa', 'setosa', 'setosa', 'setosa']\n",
+    "})"
    ]
   },
   {
@@ -90,50 +102,47 @@
        "      <td>4.9</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>...</th>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
+       "      <th>2</th>\n",
+       "      <td>3.2</td>\n",
+       "      <td>1.3</td>\n",
+       "      <td>0.2</td>\n",
+       "      <td>setosa</td>\n",
+       "      <td>4.7</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>148</th>\n",
-       "      <td>3.4</td>\n",
-       "      <td>5.4</td>\n",
-       "      <td>2.3</td>\n",
-       "      <td>virginica</td>\n",
-       "      <td>6.2</td>\n",
+       "      <th>3</th>\n",
+       "      <td>3.1</td>\n",
+       "      <td>1.5</td>\n",
+       "      <td>0.2</td>\n",
+       "      <td>setosa</td>\n",
+       "      <td>4.6</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>149</th>\n",
-       "      <td>3.0</td>\n",
-       "      <td>5.1</td>\n",
-       "      <td>1.8</td>\n",
-       "      <td>virginica</td>\n",
-       "      <td>5.9</td>\n",
+       "      <th>4</th>\n",
+       "      <td>3.6</td>\n",
+       "      <td>1.4</td>\n",
+       "      <td>0.2</td>\n",
+       "      <td>setosa</td>\n",
+       "      <td>5.0</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
-       "<p>150 rows × 5 columns</p>\n",
        "</div>"
       ],
       "text/plain": [
-       "     sepal width (cm)  petal length (cm)  petal width (cm)    species  \\\n",
-       "0                 3.5                1.4               0.2     setosa   \n",
-       "1                 3.0                1.4               0.2     setosa   \n",
-       "..                ...                ...               ...        ...   \n",
-       "148               3.4                5.4               2.3  virginica   \n",
-       "149               3.0                5.1               1.8  virginica   \n",
-       "\n",
-       "     sepal length (cm)  \n",
-       "0                  5.1  \n",
-       "1                  4.9  \n",
-       "..                 ...  \n",
-       "148                6.2  \n",
-       "149                5.9  \n",
+       "   sepal width (cm)  petal length (cm)  petal width (cm) species  \\\n",
+       "0               3.5                1.4               0.2  setosa   \n",
+       "1               3.0                1.4               0.2  setosa   \n",
+       "2               3.2                1.3               0.2  setosa   \n",
+       "3               3.1                1.5               0.2  setosa   \n",
+       "4               3.6                1.4               0.2  setosa   \n",
        "\n",
-       "[150 rows x 5 columns]"
+       "   sepal length (cm)  \n",
+       "0                5.1  \n",
+       "1                4.9  \n",
+       "2                4.7  \n",
+       "3                4.6  \n",
+       "4                5.0  "
       ]
      },
      "execution_count": 3,
@@ -482,37 +491,34 @@
        "      <td>setosa</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>...</th>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
+       "      <th>2</th>\n",
+       "      <td>4.7</td>\n",
+       "      <td>3.2</td>\n",
+       "      <td>setosa</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>148</th>\n",
-       "      <td>6.2</td>\n",
-       "      <td>3.4</td>\n",
-       "      <td>virginica</td>\n",
+       "      <th>3</th>\n",
+       "      <td>4.6</td>\n",
+       "      <td>3.1</td>\n",
+       "      <td>setosa</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>149</th>\n",
-       "      <td>5.9</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>virginica</td>\n",
+       "      <th>4</th>\n",
+       "      <td>5.0</td>\n",
+       "      <td>3.6</td>\n",
+       "      <td>setosa</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
-       "<p>150 rows × 3 columns</p>\n",
        "</div>"
       ],
       "text/plain": [
-       "     sepal length (cm)  sepal width (cm)    species\n",
-       "0                  5.1               3.5     setosa\n",
-       "1                  4.9               3.0     setosa\n",
-       "..                 ...               ...        ...\n",
-       "148                6.2               3.4  virginica\n",
-       "149                5.9               3.0  virginica\n",
-       "\n",
-       "[150 rows x 3 columns]"
+       "   sepal length (cm)  sepal width (cm) species\n",
+       "0                5.1               3.5  setosa\n",
+       "1                4.9               3.0  setosa\n",
+       "2                4.7               3.2  setosa\n",
+       "3                4.6               3.1  setosa\n",
+       "4                5.0               3.6  setosa"
       ]
      },
      "execution_count": 6,
@@ -576,50 +582,40 @@
        "      <td>setosa</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>...</th>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
+       "      <th>2</th>\n",
+       "      <td>4.7</td>\n",
+       "      <td>3.2</td>\n",
+       "      <td>1.3</td>\n",
+       "      <td>0.2</td>\n",
+       "      <td>setosa</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>148</th>\n",
-       "      <td>6.2</td>\n",
-       "      <td>3.4</td>\n",
-       "      <td>5.4</td>\n",
-       "      <td>2.3</td>\n",
-       "      <td>virginica</td>\n",
+       "      <th>3</th>\n",
+       "      <td>4.6</td>\n",
+       "      <td>3.1</td>\n",
+       "      <td>1.5</td>\n",
+       "      <td>0.2</td>\n",
+       "      <td>setosa</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>149</th>\n",
-       "      <td>5.9</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>5.1</td>\n",
-       "      <td>1.8</td>\n",
-       "      <td>virginica</td>\n",
+       "      <th>4</th>\n",
+       "      <td>5.0</td>\n",
+       "      <td>3.6</td>\n",
+       "      <td>1.4</td>\n",
+       "      <td>0.2</td>\n",
+       "      <td>setosa</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
-       "<p>150 rows × 5 columns</p>\n",
        "</div>"
       ],
       "text/plain": [
-       "     sepal length (cm)  sepal width (cm)  petal_length  petal width (cm)  \\\n",
-       "0                  5.1               3.5           1.4               0.2   \n",
-       "1                  4.9               3.0           1.4               0.2   \n",
-       "..                 ...               ...           ...               ...   \n",
-       "148                6.2               3.4           5.4               2.3   \n",
-       "149                5.9               3.0           5.1               1.8   \n",
-       "\n",
-       "       species  \n",
-       "0       setosa  \n",
-       "1       setosa  \n",
-       "..         ...  \n",
-       "148  virginica  \n",
-       "149  virginica  \n",
-       "\n",
-       "[150 rows x 5 columns]"
+       "   sepal length (cm)  sepal width (cm)  petal_length  petal width (cm) species\n",
+       "0                5.1               3.5           1.4               0.2  setosa\n",
+       "1                4.9               3.0           1.4               0.2  setosa\n",
+       "2                4.7               3.2           1.3               0.2  setosa\n",
+       "3                4.6               3.1           1.5               0.2  setosa\n",
+       "4                5.0               3.6           1.4               0.2  setosa"
       ]
      },
      "execution_count": 7,
@@ -663,7 +659,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.7"
+   "version": "3.6.8"
   },
   "toc": {
    "base_numbering": 1,
@@ -680,5 +676,5 @@
   }
  },
  "nbformat": 4,
- "nbformat_minor": 2
+ "nbformat_minor": 4
 }
diff --git a/examples/examples-dplyr-funcs.ipynb b/examples/examples-dplyr-funcs.ipynb
index 098d7bda..014c313d 100644
--- a/examples/examples-dplyr-funcs.ipynb
+++ b/examples/examples-dplyr-funcs.ipynb
@@ -82,6 +82,15 @@
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>0</th>\n",
+       "      <td>pandas</td>\n",
+       "      <td>pandas-dev</td>\n",
+       "      <td>python</td>\n",
+       "      <td>17800</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
        "      <td>dplyr</td>\n",
        "      <td>tidyverse</td>\n",
        "      <td>R</td>\n",
@@ -90,7 +99,7 @@
        "      <td>0</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>1</th>\n",
+       "      <th>2</th>\n",
        "      <td>ggplot2</td>\n",
        "      <td>tidyverse</td>\n",
        "      <td>R</td>\n",
@@ -99,7 +108,7 @@
        "      <td>700</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>2</th>\n",
+       "      <th>3</th>\n",
        "      <td>plotnine</td>\n",
        "      <td>has2k1</td>\n",
        "      <td>python</td>\n",
@@ -107,25 +116,16 @@
        "      <td>NaN</td>\n",
        "      <td>0</td>\n",
        "    </tr>\n",
-       "    <tr>\n",
-       "      <th>3</th>\n",
-       "      <td>pandas</td>\n",
-       "      <td>pandas-dev</td>\n",
-       "      <td>python</td>\n",
-       "      <td>17800</td>\n",
-       "      <td>1.0</td>\n",
-       "      <td>0</td>\n",
-       "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "text/plain": [
        "       repo       owner language  stars    x  rel_stars1\n",
-       "0     dplyr   tidyverse        R   2800  2.0           0\n",
-       "1   ggplot2   tidyverse        R   3500  3.0         700\n",
-       "2  plotnine      has2k1   python   1450  NaN           0\n",
-       "3    pandas  pandas-dev   python  17800  1.0           0"
+       "0    pandas  pandas-dev   python  17800  1.0           0\n",
+       "1     dplyr   tidyverse        R   2800  2.0           0\n",
+       "2   ggplot2   tidyverse        R   3500  3.0         700\n",
+       "3  plotnine      has2k1   python   1450  NaN           0"
       ]
      },
      "execution_count": 4,
@@ -182,6 +182,16 @@
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>0</th>\n",
+       "      <td>pandas</td>\n",
+       "      <td>pandas-dev</td>\n",
+       "      <td>python</td>\n",
+       "      <td>17800</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>35600</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
        "      <td>dplyr</td>\n",
        "      <td>tidyverse</td>\n",
        "      <td>R</td>\n",
@@ -191,7 +201,7 @@
        "      <td>5600</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>1</th>\n",
+       "      <th>2</th>\n",
        "      <td>ggplot2</td>\n",
        "      <td>tidyverse</td>\n",
        "      <td>R</td>\n",
@@ -201,7 +211,7 @@
        "      <td>7000</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>2</th>\n",
+       "      <th>3</th>\n",
        "      <td>plotnine</td>\n",
        "      <td>has2k1</td>\n",
        "      <td>python</td>\n",
@@ -210,26 +220,16 @@
        "      <td>0</td>\n",
        "      <td>2900</td>\n",
        "    </tr>\n",
-       "    <tr>\n",
-       "      <th>3</th>\n",
-       "      <td>pandas</td>\n",
-       "      <td>pandas-dev</td>\n",
-       "      <td>python</td>\n",
-       "      <td>17800</td>\n",
-       "      <td>1.0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>35600</td>\n",
-       "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "text/plain": [
        "       repo       owner language  stars    x  rel_stars1  rel_stars2\n",
-       "0     dplyr   tidyverse        R   2800  2.0           0        5600\n",
-       "1   ggplot2   tidyverse        R   3500  3.0         700        7000\n",
-       "2  plotnine      has2k1   python   1450  NaN           0        2900\n",
-       "3    pandas  pandas-dev   python  17800  1.0           0       35600"
+       "0    pandas  pandas-dev   python  17800  1.0           0       35600\n",
+       "1     dplyr   tidyverse        R   2800  2.0           0        5600\n",
+       "2   ggplot2   tidyverse        R   3500  3.0         700        7000\n",
+       "3  plotnine      has2k1   python   1450  NaN           0        2900"
       ]
      },
      "execution_count": 5,
@@ -278,6 +278,15 @@
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>0</th>\n",
+       "      <td>pandas</td>\n",
+       "      <td>pandas-dev</td>\n",
+       "      <td>python</td>\n",
+       "      <td>17800</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
        "      <td>dplyr</td>\n",
        "      <td>tidyverse</td>\n",
        "      <td>R</td>\n",
@@ -286,7 +295,7 @@
        "      <td>0</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>1</th>\n",
+       "      <th>2</th>\n",
        "      <td>ggplot2</td>\n",
        "      <td>tidyverse</td>\n",
        "      <td>R</td>\n",
@@ -295,7 +304,7 @@
        "      <td>700</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>2</th>\n",
+       "      <th>3</th>\n",
        "      <td>plotnine</td>\n",
        "      <td>has2k1</td>\n",
        "      <td>python</td>\n",
@@ -303,25 +312,16 @@
        "      <td>NaN</td>\n",
        "      <td>0</td>\n",
        "    </tr>\n",
-       "    <tr>\n",
-       "      <th>3</th>\n",
-       "      <td>pandas</td>\n",
-       "      <td>pandas-dev</td>\n",
-       "      <td>python</td>\n",
-       "      <td>17800</td>\n",
-       "      <td>1.0</td>\n",
-       "      <td>0</td>\n",
-       "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "text/plain": [
        "       repo       owner language  stars    x  rel_stars1\n",
-       "0     dplyr   tidyverse        R   2800  2.0           0\n",
-       "1   ggplot2   tidyverse        R   3500  3.0         700\n",
-       "2  plotnine      has2k1   python   1450  NaN           0\n",
-       "3    pandas  pandas-dev   python  17800  1.0           0"
+       "0    pandas  pandas-dev   python  17800  1.0           0\n",
+       "1     dplyr   tidyverse        R   2800  2.0           0\n",
+       "2   ggplot2   tidyverse        R   3500  3.0         700\n",
+       "3  plotnine      has2k1   python   1450  NaN           0"
       ]
      },
      "execution_count": 6,
@@ -379,28 +379,28 @@
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>0</th>\n",
-       "      <td>ggplot2</td>\n",
-       "      <td>tidyverse</td>\n",
-       "      <td>R</td>\n",
-       "      <td>3500</td>\n",
-       "      <td>3.0</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>1</th>\n",
        "      <td>pandas</td>\n",
        "      <td>pandas-dev</td>\n",
        "      <td>python</td>\n",
        "      <td>17800</td>\n",
        "      <td>1.0</td>\n",
        "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>ggplot2</td>\n",
+       "      <td>tidyverse</td>\n",
+       "      <td>R</td>\n",
+       "      <td>3500</td>\n",
+       "      <td>3.0</td>\n",
+       "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "text/plain": [
        "      repo       owner language  stars    x\n",
-       "0  ggplot2   tidyverse        R   3500  3.0\n",
-       "1   pandas  pandas-dev   python  17800  1.0"
+       "0   pandas  pandas-dev   python  17800  1.0\n",
+       "1  ggplot2   tidyverse        R   3500  3.0"
       ]
      },
      "execution_count": 7,
@@ -537,23 +537,23 @@
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>0</th>\n",
+       "      <td>python</td>\n",
+       "      <td>pandas</td>\n",
+       "      <td>16350</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
        "      <td>R</td>\n",
        "      <td>dplyr</td>\n",
        "      <td>0</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>1</th>\n",
+       "      <th>2</th>\n",
        "      <td>R</td>\n",
        "      <td>ggplot2</td>\n",
        "      <td>700</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>2</th>\n",
-       "      <td>python</td>\n",
-       "      <td>pandas</td>\n",
-       "      <td>16350</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
        "      <th>3</th>\n",
        "      <td>python</td>\n",
        "      <td>plotnine</td>\n",
@@ -565,9 +565,9 @@
       ],
       "text/plain": [
        "  language      repo  rel_stars1\n",
-       "0        R     dplyr           0\n",
-       "1        R   ggplot2         700\n",
-       "2   python    pandas       16350\n",
+       "0   python    pandas       16350\n",
+       "1        R     dplyr           0\n",
+       "2        R   ggplot2         700\n",
        "3   python  plotnine           0"
       ]
      },
@@ -723,7 +723,7 @@
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
-       "      <th>0</th>\n",
+       "      <th>3</th>\n",
        "      <td>plotnine</td>\n",
        "      <td>has2k1</td>\n",
        "      <td>python</td>\n",
@@ -747,7 +747,7 @@
        "      <td>3.0</td>\n",
        "    </tr>\n",
        "    <tr>\n",
-       "      <th>3</th>\n",
+       "      <th>0</th>\n",
        "      <td>pandas</td>\n",
        "      <td>pandas-dev</td>\n",
        "      <td>python</td>\n",
@@ -760,10 +760,10 @@
       ],
       "text/plain": [
        "       repo       owner language  stars    x\n",
-       "0  plotnine      has2k1   python   1450  NaN\n",
+       "3  plotnine      has2k1   python   1450  NaN\n",
        "1     dplyr   tidyverse        R   2800  2.0\n",
        "2   ggplot2   tidyverse        R   3500  3.0\n",
-       "3    pandas  pandas-dev   python  17800  1.0"
+       "0    pandas  pandas-dev   python  17800  1.0"
       ]
      },
      "execution_count": 11,
@@ -812,7 +812,7 @@
     {
      "data": {
       "text/plain": [
-       "array(['pandas', 'dplyr', 'wat', 'wat'], dtype='<U6')"
+       "array(['pandas', 'dplyr', 'wat', 'wat'], dtype=object)"
       ]
      },
      "execution_count": 13,
@@ -894,7 +894,7 @@
        "      <th>0</th>\n",
        "      <td>R</td>\n",
        "      <td>repo      owner  stars    x\n",
-       "0    dplyr  ...</td>\n",
+       "1    dplyr  ...</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>1</th>\n",
@@ -909,7 +909,7 @@
       "text/plain": [
        "  language                                               data\n",
        "0        R        repo      owner  stars    x\n",
-       "0    dplyr  ...\n",
+       "1    dplyr  ...\n",
        "1   python         repo       owner  stars    x\n",
        "0    panda..."
       ]
@@ -1908,7 +1908,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.7"
+   "version": "3.6.8"
   },
   "toc": {
    "base_numbering": 1,
diff --git a/examples/examples-postgres.ipynb b/examples/examples-postgres.ipynb
index 7ea34ac7..6bf77a0b 100644
--- a/examples/examples-postgres.ipynb
+++ b/examples/examples-postgres.ipynb
@@ -17,7 +17,7 @@
     {
      "data": {
       "text/plain": [
-       "<sqlalchemy.engine.result.ResultProxy at 0x10670ac18>"
+       "<sqlalchemy.engine.result.ResultProxy at 0x11c1f8320>"
       ]
      },
      "execution_count": 1,
@@ -80,7 +80,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": 7,
    "metadata": {},
    "outputs": [
     {
@@ -138,7 +138,7 @@
        "0        1   2  jack@msn.com    2"
       ]
      },
-     "execution_count": 2,
+     "execution_count": 7,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -146,6 +146,7 @@
    "source": [
     "from siuba import *\n",
     "from siuba.sql.verbs import LazyTbl, collect, show_query\n",
+    "from siuba.sql.dply.vector import dense_rank\n",
     "import siuba.meta_hook.sqlalchemy.sql.functions as F\n",
     "\n",
     "from sqlalchemy import sql\n",
@@ -156,7 +157,7 @@
     "#tbl_addresses >> mutate(_, num = dense_rank(_.id)) >> show_query(_)\n",
     "q = (tbl_addresses\n",
     "  >> group_by(\"user_id\")\n",
-    "  >> mutate(num = _.id.dense_rank())\n",
+    "  >> mutate(num = dense_rank(_.id))\n",
     "  >> filter(\n",
     "       _.id > _.id.min(),\n",
     "       _.email_address.str.startswith(\"jack\")\n",
@@ -1919,7 +1920,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.7"
+   "version": "3.6.8"
   },
   "toc": {
    "base_numbering": 1,
@@ -1941,5 +1942,5 @@
   }
  },
  "nbformat": 4,
- "nbformat_minor": 2
+ "nbformat_minor": 4
 }
diff --git a/examples/examples-siu.ipynb b/examples/examples-siu.ipynb
index 64dad2b3..4eaeb55f 100644
--- a/examples/examples-siu.ipynb
+++ b/examples/examples-siu.ipynb
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "> 📢: **This document was used during early development of siuba. See the [siuba intro doc](https://siuba.readthedocs.io/en/latest/api_table_core/03_select.html).**\n"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 1,
@@ -11,14 +18,14 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 8,
+   "execution_count": 2,
    "metadata": {},
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "_.somecol.min(, )\n"
+      "_.somecol.min()\n"
      ]
     },
     {
@@ -27,7 +34,7 @@
        "5"
       ]
      },
-     "execution_count": 8,
+     "execution_count": 2,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -84,7 +91,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": 3,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -93,7 +100,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 4,
    "metadata": {},
    "outputs": [
     {
@@ -102,7 +109,7 @@
        "['aa', 'bb', 'cc']"
       ]
      },
-     "execution_count": 3,
+     "execution_count": 4,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -114,7 +121,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 4,
+   "execution_count": 5,
    "metadata": {},
    "outputs": [
     {
@@ -123,7 +130,7 @@
        "['A', 'B', 'C']"
       ]
      },
-     "execution_count": 4,
+     "execution_count": 5,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -135,7 +142,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 6,
    "metadata": {},
    "outputs": [
     {
@@ -144,7 +151,7 @@
        "1"
       ]
      },
-     "execution_count": 5,
+     "execution_count": 6,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -165,7 +172,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": 7,
    "metadata": {},
    "outputs": [
     {
@@ -174,7 +181,7 @@
        "[0, 1]"
       ]
      },
-     "execution_count": 6,
+     "execution_count": 7,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -195,7 +202,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 7,
+   "execution_count": 8,
    "metadata": {},
    "outputs": [
     {
@@ -204,7 +211,7 @@
        "[1, 3]"
       ]
      },
-     "execution_count": 7,
+     "execution_count": 8,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -217,7 +224,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 8,
+   "execution_count": 9,
    "metadata": {},
    "outputs": [
     {
@@ -226,7 +233,7 @@
        "[0, 0]"
       ]
      },
-     "execution_count": 8,
+     "execution_count": 9,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -290,7 +297,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 9,
+   "execution_count": 10,
    "metadata": {},
    "outputs": [
     {
@@ -316,7 +323,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 10,
+   "execution_count": 11,
    "metadata": {},
    "outputs": [
     {
@@ -333,7 +340,7 @@
        "└─2"
       ]
      },
-     "execution_count": 10,
+     "execution_count": 11,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -351,7 +358,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 11,
+   "execution_count": 12,
    "metadata": {},
    "outputs": [
     {
@@ -360,7 +367,7 @@
        "{'a', 'b', 'c'}"
       ]
      },
-     "execution_count": 11,
+     "execution_count": 12,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -401,14 +408,14 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 12,
+   "execution_count": 13,
    "metadata": {},
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "<built-in function add>(1, _(a, ) + _(b, ), )\n"
+      "<built-in function add>(1,_('a') + _('b'))\n"
      ]
     },
     {
@@ -417,7 +424,7 @@
        "4"
       ]
      },
-     "execution_count": 12,
+     "execution_count": 13,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -435,7 +442,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 13,
+   "execution_count": 14,
    "metadata": {},
    "outputs": [
     {
@@ -446,7 +453,7 @@
        "└─{'a': [1, 2, 3]}"
       ]
      },
-     "execution_count": 13,
+     "execution_count": 14,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -457,7 +464,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 14,
+   "execution_count": 15,
    "metadata": {},
    "outputs": [
     {
@@ -472,7 +479,7 @@
        "  └─'b'"
       ]
      },
-     "execution_count": 14,
+     "execution_count": 15,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -483,7 +490,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 15,
+   "execution_count": 16,
    "metadata": {},
    "outputs": [
     {
@@ -499,7 +506,7 @@
        "  └─'b'"
       ]
      },
-     "execution_count": 15,
+     "execution_count": 16,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -525,7 +532,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 16,
+   "execution_count": 17,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -535,38 +542,40 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 17,
+   "execution_count": 18,
    "metadata": {},
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "201 µs ± 10.4 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)\n"
+      "212 µs ± 50.2 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)\n"
      ]
     }
    ],
    "source": [
     "%%timeit\n",
+    "# NBVAL_IGNORE_OUTPUT\n",
     "\n",
     "x = lmap(_['a'], l)"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 18,
+   "execution_count": 19,
    "metadata": {},
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "8.18 µs ± 529 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)\n"
+      "7.29 µs ± 199 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)\n"
      ]
     }
    ],
    "source": [
     "%%timeit\n",
+    "# NBVAL_IGNORE_OUTPUT\n",
     "\n",
     "x = lmap(lambda x: x['a'], l)"
    ]
@@ -587,7 +596,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
+   "execution_count": 20,
    "metadata": {},
    "outputs": [
     {
@@ -596,7 +605,7 @@
        "['a', _, _, _]"
       ]
      },
-     "execution_count": 19,
+     "execution_count": 20,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -616,7 +625,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 20,
+   "execution_count": 21,
    "metadata": {},
    "outputs": [
     {
@@ -625,7 +634,7 @@
        "['a', ['a'], ['a'], ['a']]"
       ]
      },
-     "execution_count": 20,
+     "execution_count": 21,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -662,9 +671,6 @@
   }
  ],
  "metadata": {
-  "jupytext": {
-   "formats": "Rmd"
-  },
   "kernelspec": {
    "display_name": "Python 3",
    "language": "python",
@@ -680,7 +686,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.7"
+   "version": "3.6.8"
   },
   "toc": {
    "base_numbering": 1,
@@ -702,5 +708,5 @@
   }
  },
  "nbformat": 4,
- "nbformat_minor": 2
+ "nbformat_minor": 4
 }
diff --git a/examples/examples-varspec.ipynb b/examples/examples-varspec.ipynb
index 3b65efd5..afdc4e4f 100644
--- a/examples/examples-varspec.ipynb
+++ b/examples/examples-varspec.ipynb
@@ -123,7 +123,7 @@
     {
      "data": {
       "text/plain": [
-       "Var('_.startswith(a, )', negated = False, alias = None)"
+       "Var('_.startswith('a')', negated = False, alias = None)"
       ]
      },
      "execution_count": 5,
@@ -153,7 +153,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.7"
+   "version": "3.6.8"
   },
   "toc": {
    "base_numbering": 1,
@@ -170,5 +170,5 @@
   }
  },
  "nbformat": 4,
- "nbformat_minor": 2
+ "nbformat_minor": 4
 }
diff --git a/requirements-test.txt b/requirements-test.txt
new file mode 100644
index 00000000..6f5d0100
--- /dev/null
+++ b/requirements-test.txt
@@ -0,0 +1,37 @@
+appnope==0.1.0
+attrs==19.3.0
+backcall==0.1.0
+coverage==5.0.3
+decorator==4.4.2
+hypothesis==5.6.0
+importlib-metadata==1.5.0
+ipykernel==5.1.4
+ipython==7.13.0
+ipython-genutils==0.2.0
+jedi==0.16.0
+jsonschema==3.2.0
+jupyter-client==6.0.0
+jupyter-core==4.6.3
+more-itertools==8.2.0
+nbformat==5.0.4
+nbval==0.9.5
+packaging==20.3
+parso==0.6.2
+pexpect==4.8.0
+pickleshare==0.7.5
+pluggy==0.13.1
+prompt-toolkit==3.0.3
+ptyprocess==0.6.0
+py==1.8.1
+Pygments==2.5.2
+pyparsing==2.4.6
+pyrsistent==0.15.7
+pytest==5.3.5
+python-dateutil==2.8.1
+pyzmq==19.0.0
+six==1.14.0
+sortedcontainers==2.1.0
+tornado==6.0.4
+traitlets==4.3.3
+wcwidth==0.1.8
+zipp==3.1.0
diff --git a/setup.py b/setup.py
index d0e22977..cdf8ee39 100644
--- a/setup.py
+++ b/setup.py
@@ -7,15 +7,18 @@
 _version_re = re.compile(r'__version__\s+=\s+(.*)')
 
 with open('siuba/__init__.py', 'rb') as f:
-    version = str(ast.literal_eval(_version_re.search(
+    VERSION = str(ast.literal_eval(_version_re.search(
         f.read().decode('utf-8')).group(1)))
 
+with open('README.md') as f:
+    README = f.read()
+
 # setup -----------------------------------------------------------------------
 
 setup(
     name='siuba',
     packages=find_packages(),
-    version=version,
+    version=VERSION,
     description='A package for quick, scrappy analyses with pandas and SQL',
     author='Michael Chow',
     license='MIT',
@@ -29,6 +32,8 @@
     ],
     python_requires=">=3.6",
     include_package_data=True,
+    long_description=README,
+    long_description_content_type="text/markdown",
     classifiers=[
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.6',