diff --git a/src/big/big_decimal.cr b/src/big/big_decimal.cr
index aaa35a374092..8450ce2c7317 100644
--- a/src/big/big_decimal.cr
+++ b/src/big/big_decimal.cr
@@ -199,8 +199,8 @@ struct BigDecimal < Number
   # defines a maximum number of iterations in case the division is not exact.
   #
   # ```
-  # BigDecimal(1).div(BigDecimal(2))    # => BigDecimal(@value=5, @scale=2)
-  # BigDecimal(1).div(BigDecimal(3), 5) # => BigDecimal(@value=33333, @scale=5)
+  # BigDecimal.new(1).div(BigDecimal.new(2))    # => BigDecimal(@value=5, @scale=2)
+  # BigDecimal.new(1).div(BigDecimal.new(3), 5) # => BigDecimal(@value=33333, @scale=5)
   # ```
   def div(other : BigDecimal, max_div_iterations = DEFAULT_MAX_DIV_ITERATIONS) : BigDecimal
     check_division_by_zero other
@@ -531,7 +531,7 @@ struct Int
   # Converts `self` to `BigDecimal`.
   # ```
   # require "big"
-  # 1212341515125412412412421.to_big_d
+  # 12123415151254124124.to_big_d
   # ```
   def to_big_d
     BigDecimal.new(self)
diff --git a/src/big/big_int.cr b/src/big/big_int.cr
index d3430bdf2d54..e880399ac106 100644
--- a/src/big/big_int.cr
+++ b/src/big/big_int.cr
@@ -27,7 +27,7 @@ struct BigInt < Int
   #
   # ```
   # BigInt.new("123456789123456789123456789123456789") # => 123456789123456789123456789123456789
-  # BigInt.new("123_456_789_123_456_789_123_456_789")  # => 123456789012345678901234567890
+  # BigInt.new("123_456_789_123_456_789_123_456_789")  # => 123456789123456789123456789
   # BigInt.new("1234567890ABCDEF", base: 16)           # => 1311768467294899695
   # ```
   def initialize(str : String, base = 10)
diff --git a/src/enumerable.cr b/src/enumerable.cr
index bf8064049060..592beea46044 100644
--- a/src/enumerable.cr
+++ b/src/enumerable.cr
@@ -1124,7 +1124,7 @@ module Enumerable(T)
   # `pattern === element` is false.
   #
   # ```
-  # [1, 3, 2, 5, 4, 6].reject(3..5).should eq([1, 2, 6])
+  # [1, 3, 2, 5, 4, 6].reject(3..5) # => [1, 2, 6]
   # ```
   def reject(pattern)
     reject { |e| pattern === e }
@@ -1160,7 +1160,7 @@ module Enumerable(T)
   # `pattern === element`.
   #
   # ```
-  # [1, 3, 2, 5, 4, 6].select(3..5).should eq([3, 5, 4])
+  # [1, 3, 2, 5, 4, 6].select(3..5) # => [3, 5, 4]
   # ```
   def select(pattern)
     self.select { |e| pattern === e }
diff --git a/src/hash.cr b/src/hash.cr
index 8e268004fabf..269e8bb873c6 100644
--- a/src/hash.cr
+++ b/src/hash.cr
@@ -688,7 +688,7 @@ class Hash(K, V)
   #
   # ```
   # hash = {:a => 1, :b => 2, :c => 3}
-  # hash.transform_keys { |key| key.to_s } # => {"A" => 1, "B" => 2, "C" => 3}
+  # hash.transform_keys { |key| key.to_s } # => {"a" => 1, "b" => 2, "c" => 3}
   # ```
   def transform_keys(&block : K -> K2) forall K2
     each_with_object({} of K2 => V) do |(key, value), memo|
@@ -702,6 +702,7 @@ class Hash(K, V)
   # ```
   # hash = {:a => 1, :b => 2, :c => 3}
   # hash.transform_values { |value| value + 1 } # => {:a => 2, :b => 3, :c => 4}
+  # ```
   def transform_values(&block : V -> V2) forall V2
     each_with_object({} of K => V2) do |(key, value), memo|
       memo[key] = yield(value)
@@ -715,6 +716,7 @@ class Hash(K, V)
   # hash = {:a => 1, :b => 2, :c => 3}
   # hash.transform_values! { |value| value + 1 }
   # hash # => {:a => 2, :b => 3, :c => 4}
+  # ```
   def transform_values!(&block : V -> V)
     current = @first
     while current
diff --git a/src/http/params.cr b/src/http/params.cr
index fc1649313daf..2f5535dda73d 100644
--- a/src/http/params.cr
+++ b/src/http/params.cr
@@ -172,8 +172,8 @@ module HTTP
     # Returns `true` if params is empty.
     #
     # ```
-    # Params.new.empty?                              # => true
-    # Params.parse("foo=bar&foo=baz&qux=zoo").empty? # => false
+    # HTTP::Params.new.empty?                              # => true
+    # HTTP::Params.parse("foo=bar&foo=baz&qux=zoo").empty? # => false
     # ```
     delegate empty?, to: raw_params
 
diff --git a/src/http/server.cr b/src/http/server.cr
index f77a89c98782..30fcfbfc9514 100644
--- a/src/http/server.cr
+++ b/src/http/server.cr
@@ -296,9 +296,9 @@ class HTTP::Server
   #
   # ```
   # server = HTTP::Server.new { }
-  # server.bind("tcp://localhost:80")  # => Socket::IPAddress.new("127.0.0.1", 8080)
-  # server.bind("unix:///tmp/server.sock")  # => Socket::UNIXAddress.new("/tmp/server.sock")
-  # server.bind("tls://127.0.0.1:443?key=private.key&cert=certificate.cert&ca=ca.crt)  # => Socket::IPAddress.new("127.0.0.1", 443)
+  # server.bind("tcp://localhost:80")                                                  # => Socket::IPAddress.new("127.0.0.1", 8080)
+  # server.bind("unix:///tmp/server.sock")                                             # => Socket::UNIXAddress.new("/tmp/server.sock")
+  # server.bind("tls://127.0.0.1:443?key=private.key&cert=certificate.cert&ca=ca.crt") # => Socket::IPAddress.new("127.0.0.1", 443)
   # ```
   def bind(uri : String) : Socket::Address
     bind(URI.parse(uri))
diff --git a/src/humanize.cr b/src/humanize.cr
index 34464eb562b9..ea4f85a2b73b 100644
--- a/src/humanize.cr
+++ b/src/humanize.cr
@@ -98,7 +98,7 @@ struct Number
   #
   # ```
   # 1_200_000_000.humanize # => "1.2G"
-  # 0.000_000_012.humanize # => "12n"
+  # 0.000_000_012.humanize # => "12.0n"
   # ```
   #
   # If *significant* is `false`, the number of *precision* digits is preserved
@@ -139,7 +139,7 @@ struct Number
   #
   # ```
   # 1_200_000_000.humanize # => "1.2G"
-  # 0.000_000_012.humanize # => "12n"
+  # 0.000_000_012.humanize # => "12.0n"
   # ```
   #
   # If *significant* is `false`, the number of *precision* digits is preserved
@@ -172,7 +172,7 @@ struct Number
   # end
   #
   # humanize_length(1_420) # => "1.42 km"
-  # humanize_length(0.23)  # => "23 cm"
+  # humanize_length(0.23)  # => "23.0 cm"
   # ```
   #
   # See `Int#humanize_bytes` to format a file size.
@@ -275,9 +275,9 @@ struct Int
   #
   # ```
   # 1.humanize_bytes                        # => "1B"
-  # 1024.humanize_bytes                     # => "1.0KB"
-  # 1536.humanize_bytes                     # => "1.5KB"
-  # 524288.humanize_bytes                   # => "512KB"
+  # 1024.humanize_bytes                     # => "1.0kiB"
+  # 1536.humanize_bytes                     # => "1.5kiB"
+  # 524288.humanize_bytes                   # => "512kiB"
   # 1073741824.humanize_bytes(format: :IEC) # => "1.0GiB"
   # ```
   #
diff --git a/src/iterator.cr b/src/iterator.cr
index 5f7bf0d60620..c7a872078a8d 100644
--- a/src/iterator.cr
+++ b/src/iterator.cr
@@ -177,7 +177,7 @@ module Iterator(T)
   # iterators to chain is large (usually greater than 4) or undetermined.
   #
   # ```
-  # array_of_iters = [[1], [2, 3], [4, 5, 6]]
+  # array_of_iters = [[1], [2, 3], [4, 5, 6]].each.map &.each
   # iter = Iterator(Int32).chain array_of_iters
   # iter.next # => 1
   # iter.next # => 2
@@ -728,7 +728,7 @@ module Iterator(T)
   # where `pattern === element` does not hold.
   #
   # ```
-  # iter = [2, 3, 1, 5, 4, 6].reject(3..5)
+  # iter = [2, 3, 1, 5, 4, 6].each.reject(3..5)
   # iter.next # => 2
   # iter.next # => 1
   # iter.next # => 6
@@ -785,7 +785,7 @@ module Iterator(T)
   # where `pattern === element`.
   #
   # ```
-  # iter = [1, 3, 2, 5, 4, 6].select(3..5)
+  # iter = [1, 3, 2, 5, 4, 6].each.select(3..5)
   # iter.next # => 3
   # iter.next # => 5
   # iter.next # => 4
@@ -1310,7 +1310,7 @@ module Iterator(T)
   # iter.next # => ['d', 'E']
   # iter.next # => ['F']
   # iter.next # => ['g', 'h']
-  # iter.next # => Iterator::Stop
+  # iter.next # => Iterator::Stop::INSTANCE
   # ```
   #
   # By default, a new array is created and yielded for each slice when invoking `next`.
@@ -1338,7 +1338,7 @@ module Iterator(T)
   # iter.next # => ['d', 'E']
   # iter.next # => ['F']
   # iter.next # => ['g', 'h']
-  # iter.next # => Iterator::Stop
+  # iter.next # => Iterator::Stop::INSTANCE
   # ```
   #
   # By default, a new array is created and yielded for each slice when invoking `next`.
@@ -1416,7 +1416,7 @@ module Iterator(T)
   # iter.next # => ['C', 'd']
   # iter.next # => ['E']
   # iter.next # => ['F', 'g', 'h']
-  # iter.next # => Iterator::Stop
+  # iter.next # => Iterator::Stop::INSTANCE
   # ```
   #
   # By default, a new array is created and yielded for each slice when invoking `next`.
@@ -1444,7 +1444,7 @@ module Iterator(T)
   # iter.next # => ['C', 'd']
   # iter.next # => ['E']
   # iter.next # => ['F', 'g', 'h']
-  # iter.next # => Iterator::Stop
+  # iter.next # => Iterator::Stop::INSTANCE
   # ```
   #
   # By default, a new array is created and yielded for each slice when invoking `next`.
@@ -1528,7 +1528,7 @@ module Iterator(T)
   # iter.next # => [9, 10, 11, 12]
   # iter.next # => [15, 16]
   # iter.next # => [19, 20, 21]
-  # iter.next # => Iterator::Stop
+  # iter.next # => Iterator::Stop::INSTANCE
   # ```
   #
   # By default, a new array is created and yielded for each slice when invoking `next`.
@@ -1558,7 +1558,7 @@ module Iterator(T)
   # iter.next # => [9, 10, 11, 12]
   # iter.next # => [15, 16]
   # iter.next # => [19, 20, 21]
-  # iter.next # => Iterator::Stop
+  # iter.next # => Iterator::Stop::INSTANCE
   # ```
   #
   # By default, a new array is created and yielded for each slice when invoking `next`.
diff --git a/src/kernel.cr b/src/kernel.cr
index 6c50ca73491c..81a47527ed4a 100644
--- a/src/kernel.cr
+++ b/src/kernel.cr
@@ -276,8 +276,8 @@ end
 # sprintf "%20.8g", 1234.56789 # => "           1234.5679"
 # sprintf "%20.8g", 123456789  # => "       1.2345679e+08"
 # sprintf "%20.8G", 123456789  # => "       1.2345679E+08"
-# sprintf "%20.8g", -123456789 # => "       -1.2345679e+08"
-# sprintf "%20.8G", -123456789 # => "       -1.2345679E+08"
+# sprintf "%20.8g", -123456789 # => "      -1.2345679e+08"
+# sprintf "%20.8G", -123456789 # => "      -1.2345679E+08"
 # ```
 #
 # The field width is an optional integer, followed optionally by a
@@ -289,7 +289,7 @@ end
 # sprintf "%20d", 123   # => "                 123"
 # sprintf "%+20d", 123  # => "                +123"
 # sprintf "%020d", 123  # => "00000000000000000123"
-# sprintf "%+020d", 12  # => "+0000000000000000123"
+# sprintf "%+020d", 123 # => "+0000000000000000123"
 # sprintf "% 020d", 123 # => " 0000000000000000123"
 # sprintf "%-20d", 123  # => "123                 "
 # sprintf "%-+20d", 123 # => "+123                "
@@ -315,7 +315,7 @@ end
 # sprintf "%020.8o", 123  # => "00000000000000000173"
 # sprintf "%20.8x", 123   # => "                  7b"
 # sprintf "%020.8x", 123  # => "0000000000000000007b"
-# sprintf "%20.8b", 123   # => "            01111011"
+# sprintf "%20.8b", 123   # => "             1111011"
 # sprintf "%20.8d", -123  # => "                -123"
 # sprintf "%020.8d", -123 # => "0000000000000000-123"
 # sprintf "%20.8o", -123  # => "                -173"
diff --git a/src/mime.cr b/src/mime.cr
index 40e73a25effe..bb033dc72a43 100644
--- a/src/mime.cr
+++ b/src/mime.cr
@@ -5,8 +5,8 @@ require "crystal/system/mime"
 # ```
 # require "mime"
 #
-# MIME.from_extension(".html")         # => "text/html; charset=utf-8"
-# MIME.from_filename("path/file.html") # => "text/html; charset=utf-8"
+# MIME.from_extension(".html")         # => "text/html"
+# MIME.from_filename("path/file.html") # => "text/html"
 # ```
 #
 # The registry will be populated with some default values (see `DEFAULT_TYPES`)
diff --git a/src/mime/multipart/builder.cr b/src/mime/multipart/builder.cr
index 006f6e66b138..77d7e9461462 100644
--- a/src/mime/multipart/builder.cr
+++ b/src/mime/multipart/builder.cr
@@ -27,7 +27,7 @@ module MIME::Multipart
     # ```
     # io = IO::Memory.new # This is a stub. Actually, any IO can be used.
     # builder = MIME::Multipart::Builder.new(io, "a4VF")
-    # builder.content_type("mixed") # => "multipart/mixed; boundary=\"a4VF\""
+    # builder.content_type("mixed") # => "multipart/mixed; boundary=a4VF"
     # ```
     def content_type(subtype = "mixed")
       MIME::MediaType.new("multipart/#{subtype}", {"boundary" => @boundary}).to_s
diff --git a/src/static_array.cr b/src/static_array.cr
index dedd62950fb9..650a519a6b78 100644
--- a/src/static_array.cr
+++ b/src/static_array.cr
@@ -19,7 +19,7 @@
 # ints = uninitialized Int32[3]
 # ints[0] = 0
 # ints[1] = 8
-# ints[3] = 15
+# ints[2] = 15
 # ```
 #
 # For number types there is also `Number.static_array` which can be used to initialize
diff --git a/src/tuple.cr b/src/tuple.cr
index 33eefe457443..b973c8c142aa 100644
--- a/src/tuple.cr
+++ b/src/tuple.cr
@@ -84,8 +84,8 @@ struct Tuple
   # Creates a tuple from the given array, with elements casted to the given types.
   #
   # ```
-  # Tuple(String, Int64).from(["world", 2])       # => {"world", 2}
-  # Tuple(String, Int64).from(["world", 2]).class # => {String, Int64}
+  # Tuple(String, Int64).from(["world", 2_i64])       # => {"world", 2_i64}
+  # Tuple(String, Int64).from(["world", 2_i64]).class # => {String, Int64}
   # ```
   #
   # See also: `#from`.
@@ -101,11 +101,13 @@ struct Tuple
   # This allows you to easily pass an array as individual arguments to a method.
   #
   # ```
+  # require "json"
+  #
   # def speak_about(thing : String, n : Int64)
   #   "I see #{n} #{thing}s"
   # end
   #
-  # data = JSON.parse(%(["world", 2])).as_a
+  # data = JSON.parse(%(["world", 2])).as_a.map(&.raw)
   # speak_about(*{String, Int64}.from(data)) # => "I see 2 worlds"
   # ```
   def from(array : Array)
diff --git a/src/uuid/json.cr b/src/uuid/json.cr
index 80d868913503..bd4cbe4a8d7e 100644
--- a/src/uuid/json.cr
+++ b/src/uuid/json.cr
@@ -17,7 +17,7 @@ require "uuid"
 # example = Example.from_json(%({"id": "ba714f86-cac6-42c7-8956-bcf5105e1b81"}))
 #
 # uuid = UUID.new("87b3042b-9b9a-41b7-8b15-a93d3f17025e")
-# uuid.to_json # => "87b3042b-9b9a-41b7-8b15-a93d3f17025e"
+# uuid.to_json # => "\"87b3042b-9b9a-41b7-8b15-a93d3f17025e\""
 # ```
 struct UUID
   def self.new(pull : JSON::PullParser)