From ffe2a14432431005c89a7e5e12655c0fb614f9a4 Mon Sep 17 00:00:00 2001
From: Luthaf <luthaf@luthaf.fr>
Date: Wed, 24 Aug 2022 16:48:56 +0200
Subject: [PATCH] Drop support for Python <3.7

---
 .github/workflows/tests.yml |  2 +-
 examples/indexes.py         |  2 +-
 src/chemfiles/__init__.py   |  3 ---
 src/chemfiles/_c_lib.py     |  1 -
 src/chemfiles/atom.py       | 25 +++++++----------
 src/chemfiles/cell.py       |  7 +----
 src/chemfiles/frame.py      | 25 +++++++----------
 src/chemfiles/misc.py       | 54 +++++++++++++------------------------
 src/chemfiles/property.py   | 12 +++------
 src/chemfiles/residue.py    | 17 ++++++------
 src/chemfiles/selection.py  |  5 +---
 src/chemfiles/topology.py   | 18 ++++---------
 src/chemfiles/trajectory.py | 26 ++++--------------
 src/chemfiles/utils.py      | 11 +-------
 tests/_utils.py             |  2 --
 tests/atom.py               |  3 ---
 tests/cell.py               |  3 ---
 tests/examples.py           |  3 ---
 tests/frame.py              |  3 ---
 tests/misc.py               |  3 ---
 tests/property.py           |  3 ---
 tests/residue.py            |  3 ---
 tests/selection.py          |  3 ---
 tests/topology.py           |  3 ---
 tests/trajectory.py         |  3 ---
 25 files changed, 63 insertions(+), 177 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 4edbbc4a..ee296a11 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-20.04]
-        python-version: ["2.7", "3.6", "3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10"]
         include:
           - os: windows-2019
             python-version: "3.8"
diff --git a/examples/indexes.py b/examples/indexes.py
index cb2d8b3d..85b58d2a 100644
--- a/examples/indexes.py
+++ b/examples/indexes.py
@@ -14,4 +14,4 @@
 
 print("Atoms with x < 5: ")
 for i in less_than_five:
-    print("  - {}".format(i))
+    print(f"  - {i}")
diff --git a/src/chemfiles/__init__.py b/src/chemfiles/__init__.py
index fb3d9fc3..4ded9680 100644
--- a/src/chemfiles/__init__.py
+++ b/src/chemfiles/__init__.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 from .atom import Atom
 from .cell import CellShape, UnitCell
 from .frame import Frame
diff --git a/src/chemfiles/_c_lib.py b/src/chemfiles/_c_lib.py
index 6d6f9238..edc637fe 100644
--- a/src/chemfiles/_c_lib.py
+++ b/src/chemfiles/_c_lib.py
@@ -1,4 +1,3 @@
-# -* coding: utf-8 -*
 import os
 import sys
 from ctypes import POINTER, c_double, cdll
diff --git a/src/chemfiles/atom.py b/src/chemfiles/atom.py
index 008ec19c..84bc46f3 100644
--- a/src/chemfiles/atom.py
+++ b/src/chemfiles/atom.py
@@ -1,11 +1,8 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 from ctypes import c_char_p, c_double, c_uint64
 
 from .misc import ChemfilesError
 from .property import Property
-from .utils import CxxPointer, _call_with_growing_buffer, string_type
+from .utils import CxxPointer, _call_with_growing_buffer
 
 
 class Atom(CxxPointer):
@@ -38,12 +35,10 @@ def __copy__(self):
         return Atom.from_mutable_ptr(None, self.ffi.chfl_atom_copy(self.ptr))
 
     def __repr__(self):
-        name = self.name
-        type = self.type
-        if type == name:
-            return "Atom('{}')".format(name)
+        if self.type == self.name:
+            return f"Atom('{self.name}')"
         else:
-            return "Atom('{}', '{}')".format(name, type)
+            return f"Atom('{self.name}', '{self.type}')"
 
     @property
     def mass(self):
@@ -150,10 +145,11 @@ def __getitem__(self, name):
         Get a property of this atom with the given ``name``, or raise an error
         if the property does not exists.
         """
-        if not isinstance(name, string_type):
+        if not isinstance(name, str):
             raise ChemfilesError(
-                "Invalid type {} for an atomic property name".format(type(name))
+                f"Invalid type {type(name)} for an atomic property name"
             )
+
         ptr = self.ffi.chfl_atom_get_property(self.ptr, name.encode("utf8"))
         return Property.from_mutable_ptr(self, ptr).get()
 
@@ -162,10 +158,9 @@ def __setitem__(self, name, value):
         Set a property of this atom, with the given ``name`` and ``value``.
         The new value overwrite any pre-existing property with the same name.
         """
-        if not isinstance(name, string_type):
-            raise ChemfilesError(
-                "invalid type {} for a property name".format(type(name))
-            )
+        if not isinstance(name, str):
+            raise ChemfilesError(f"invalid type {type(name)} for a property name")
+
         property = Property(value)
         self.ffi.chfl_atom_set_property(self.mut_ptr, name.encode("utf8"), property.ptr)
 
diff --git a/src/chemfiles/cell.py b/src/chemfiles/cell.py
index b708a360..a2227601 100644
--- a/src/chemfiles/cell.py
+++ b/src/chemfiles/cell.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 from ctypes import ARRAY, c_double
 from enum import IntEnum
 
@@ -63,9 +60,7 @@ def __init__(self, lengths, angles=(90.0, 90.0, 90.0)):
         else:
             if lengths.shape != (3, 3):
                 raise ChemfilesError(
-                    "expected the cell matrix to have 3x3 shape, got {}".format(
-                        lengths.shape
-                    )
+                    f"expected the cell matrix to have 3x3 shape, got {lengths.shape}"
                 )
             matrix = ARRAY(chfl_vector3d, (3))()
             matrix[0][0] = lengths[0, 0]
diff --git a/src/chemfiles/frame.py b/src/chemfiles/frame.py
index a2efc9b2..3ad6d107 100644
--- a/src/chemfiles/frame.py
+++ b/src/chemfiles/frame.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 from ctypes import POINTER, c_bool, c_char_p, c_double, c_uint64
 
 import numpy as np
@@ -11,7 +8,7 @@
 from .misc import ChemfilesError
 from .property import Property
 from .topology import Topology
-from .utils import CxxPointer, string_type
+from .utils import CxxPointer
 
 
 class FrameAtoms(object):
@@ -32,9 +29,7 @@ def __getitem__(self, index):
         associated :py:class:`Frame`.
         """
         if index >= len(self):
-            raise IndexError(
-                "atom index ({}) out of range for this frame".format(index)
-            )
+            raise IndexError(f"atom index ({index}) out of range for this frame")
         else:
             ptr = self.frame.ffi.chfl_atom_from_frame(
                 self.frame.mut_ptr, c_uint64(index)
@@ -68,7 +63,7 @@ def __copy__(self):
         return Frame.from_mutable_ptr(None, self.ffi.chfl_frame_copy(self.ptr))
 
     def __repr__(self):
-        return "Frame with {} atoms".format(len(self.atoms))
+        return f"Frame with {len(self.atoms)} atoms"
 
     @property
     def atoms(self):
@@ -325,10 +320,9 @@ def __getitem__(self, name):
         Get a property of this frame with the given ``name``, or raise an error
         if the property does not exists.
         """
-        if not isinstance(name, string_type):
-            raise ChemfilesError(
-                "Invalid type {} for a frame property name".format(type(name))
-            )
+        if not isinstance(name, str):
+            raise ChemfilesError(f"Invalid type {type(name)} for a frame property name")
+
         ptr = self.ffi.chfl_frame_get_property(self.ptr, name.encode("utf8"))
         return Property.from_mutable_ptr(self, ptr).get()
 
@@ -337,10 +331,9 @@ def __setitem__(self, name, value):
         Set a property of this frame, with the given ``name`` and ``value``.
         The new value overwrite any pre-existing property with the same name.
         """
-        if not isinstance(name, string_type):
-            raise ChemfilesError(
-                "Invalid type {} for a frame property name".format(type(name))
-            )
+        if not isinstance(name, str):
+            raise ChemfilesError(f"Invalid type {type(name)} for a frame property name")
+
         property = Property(value)
         self.ffi.chfl_frame_set_property(
             self.mut_ptr, name.encode("utf8"), property.ptr
diff --git a/src/chemfiles/misc.py b/src/chemfiles/misc.py
index 5da04929..ecd5788b 100644
--- a/src/chemfiles/misc.py
+++ b/src/chemfiles/misc.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import warnings
 from ctypes import POINTER, c_uint64, create_string_buffer
 
@@ -82,43 +79,28 @@ def _set_from_c(self, c_format_metadata):
         self.residues = c_format_metadata.residues
 
     def __repr__(self):
-        return """
-FormatMetadata for {name}
--------------------{name_underline}
-{description}
+        return f"""
+FormatMetadata for {self.name}
+-------------------{"-" * len(self.name)}
+{self.description}
 
-name      = {name}
-extension = {extension}
-reference = {reference}
+name      = {self.name}
+extension = {self.extension}
+reference = {self.reference}
 
 Capacities:
 -----------
 
-read        = {read}
-write       = {write}
-memory      = {memory}
-positions   = {positions}
-velocities  = {velocities}
-unit_cell   = {unit_cell}
-atoms       = {atoms}
-bonds       = {bonds}
-residues    = {residues}
-""".format(
-            name=self.name,
-            name_underline="-" * len(self.name),
-            description=self.description,
-            extension=self.extension,
-            reference=self.reference,
-            read=self.read,
-            write=self.write,
-            memory=self.memory,
-            positions=self.positions,
-            velocities=self.velocities,
-            unit_cell=self.unit_cell,
-            atoms=self.atoms,
-            bonds=self.bonds,
-            residues=self.residues,
-        )
+read        = {self.read}
+write       = {self.write}
+memory      = {self.memory}
+positions   = {self.positions}
+velocities  = {self.velocities}
+unit_cell   = {self.unit_cell}
+atoms       = {self.atoms}
+bonds       = {self.bonds}
+residues    = {self.residues}
+"""
 
 
 def formats_list():
@@ -162,7 +144,7 @@ def callback(message):
         try:
             function(message.decode("utf8"))
         except Exception as e:
-            message = "exception raised in warning callback: {}".format(e)
+            message = f"exception raised in warning callback: {e}"
             warnings.warn(message, ChemfilesWarning)
 
     global _CURRENT_CALLBACK
diff --git a/src/chemfiles/property.py b/src/chemfiles/property.py
index d4849916..b0853fbc 100644
--- a/src/chemfiles/property.py
+++ b/src/chemfiles/property.py
@@ -1,14 +1,10 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
-import sys
 from ctypes import c_bool, c_double
 
 import numpy as np
 
 from ._c_api import chfl_property_kind, chfl_vector3d
 from .misc import ChemfilesError
-from .utils import CxxPointer, _call_with_growing_buffer, string_type
+from .utils import CxxPointer, _call_with_growing_buffer
 
 
 class Property(CxxPointer):
@@ -26,16 +22,14 @@ def __init__(self, value):
             ptr = self.ffi.chfl_property_bool(c_bool(value))
         elif isinstance(value, (float, int)):
             ptr = self.ffi.chfl_property_double(c_double(value))
-        elif isinstance(value, string_type):
+        elif isinstance(value, str):
             ptr = self.ffi.chfl_property_string(value.encode("utf8"))
         elif _is_vector3d(value):
             value = chfl_vector3d(value[0], value[1], value[2])
             ptr = self.ffi.chfl_property_vector3d(value)
         else:
             raise ChemfilesError(
-                "can not create a Property with a value of type '{}'".format(
-                    type(value)
-                )
+                f"can not create a Property with a value of type '{type(value)}'"
             )
 
         super(Property, self).__init__(ptr, is_const=False)
diff --git a/src/chemfiles/residue.py b/src/chemfiles/residue.py
index 1996fa68..75ff1dc3 100644
--- a/src/chemfiles/residue.py
+++ b/src/chemfiles/residue.py
@@ -1,13 +1,10 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 from ctypes import c_bool, c_char_p, c_int64, c_uint64
 
 import numpy as np
 
 from .misc import ChemfilesError
 from .property import Property
-from .utils import CxxPointer, _call_with_growing_buffer, string_type
+from .utils import CxxPointer, _call_with_growing_buffer
 
 
 class ResidueAtoms(object):
@@ -90,7 +87,7 @@ def __copy__(self):
         return Residue.from_mutable_ptr(None, self.ffi.chfl_residue_copy(self.ptr))
 
     def __repr__(self):
-        return "Residue('{}') with {} atoms".format(self.name, len(self.atoms))
+        return f"Residue('{self.name}') with {len(self.atoms)} atoms"
 
     @property
     def name(self):
@@ -120,10 +117,11 @@ def __getitem__(self, name):
         Get a property of this residude with the given ``name``, or raise an
         error if the property does not exists.
         """
-        if not isinstance(name, string_type):
+        if not isinstance(name, str):
             raise ChemfilesError(
-                "Invalid type {} for a residue property name".format(type(name))
+                f"Invalid type {type(name)} for a residue property name"
             )
+
         ptr = self.ffi.chfl_residue_get_property(self.ptr, name.encode("utf8"))
         return Property.from_mutable_ptr(self, ptr).get()
 
@@ -132,10 +130,11 @@ def __setitem__(self, name, value):
         Set a property of this residue, with the given ``name`` and ``value``.
         The new value overwrite any pre-existing property with the same name.
         """
-        if not isinstance(name, string_type):
+        if not isinstance(name, str):
             raise ChemfilesError(
-                "Invalid type {} for a residue property name".format(type(name))
+                f"Invalid type {type(name)} for a residue property name"
             )
+
         property = Property(value)
         self.ffi.chfl_residue_set_property(
             self.mut_ptr, name.encode("utf8"), property.ptr
diff --git a/src/chemfiles/selection.py b/src/chemfiles/selection.py
index 79eb80b1..4994185a 100644
--- a/src/chemfiles/selection.py
+++ b/src/chemfiles/selection.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 from ctypes import c_uint64
 
 import numpy as np
@@ -33,7 +30,7 @@ def __copy__(self):
         return Selection.from_mutable_ptr(None, self.ffi.chfl_selection_copy(self.ptr))
 
     def __repr__(self):
-        return "Selection('{}')".format(self.string)
+        return f"Selection('{self.string}')"
 
     @property
     def size(self):
diff --git a/src/chemfiles/topology.py b/src/chemfiles/topology.py
index 93b2ba13..3b8a9de7 100644
--- a/src/chemfiles/topology.py
+++ b/src/chemfiles/topology.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 from ctypes import c_bool, c_uint64
 from enum import IntEnum
 
@@ -54,9 +51,7 @@ def __getitem__(self, index):
         associated :py:class:`Topology`.
         """
         if index >= len(self):
-            raise IndexError(
-                "atom index ({}) out of range for this topology".format(index)
-            )
+            raise IndexError(f"atom index ({index}) out of range for this topology")
         else:
             ptr = self.topology.ffi.chfl_atom_from_topology(
                 self.topology.mut_ptr, c_uint64(index)
@@ -110,9 +105,7 @@ def __getitem__(self, index):
         topology does not necessarily match the residue id.
         """
         if index >= len(self):
-            raise IndexError(
-                "residue index ({}) out of range for this topology".format(index)
-            )
+            raise IndexError(f"residue index ({index}) out of range for this topology")
         else:
             ptr = self.topology.ffi.chfl_residue_from_topology(
                 self.topology.ptr, c_uint64(index)
@@ -151,7 +144,7 @@ def __copy__(self):
         return Topology.from_mutable_ptr(None, self.ffi.chfl_topology_copy(self.ptr))
 
     def __repr__(self):
-        return "Topology with {} atoms".format(len(self.atoms))
+        return f"Topology with {len(self.atoms)} atoms"
 
     @property
     def atoms(self):
@@ -186,9 +179,8 @@ def residue_for_atom(self, index):
         atom is not part of a residue.
         """
         if index >= len(self.atoms):
-            raise IndexError(
-                "residue index ({}) out of range for this topology".format(index)
-            )
+            raise IndexError(f"residue index ({index}) out of range for this topology")
+
         ptr = self.ffi.chfl_residue_for_atom(self.ptr, c_uint64(index))
         if ptr:
             return Residue.from_const_ptr(self, ptr)
diff --git a/src/chemfiles/trajectory.py b/src/chemfiles/trajectory.py
index cb1b83cc..1773c864 100644
--- a/src/chemfiles/trajectory.py
+++ b/src/chemfiles/trajectory.py
@@ -1,21 +1,9 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
-import sys
 from ctypes import c_char_p, c_uint64
 
 from .frame import Frame, Topology
 from .misc import ChemfilesError
 from .utils import CxxPointer, _call_with_growing_buffer
 
-# Python 2 compatibility
-if sys.hexversion >= 0x03000000:
-    unicode_string = str
-    bytes_string = bytes
-else:
-    unicode_string = unicode  # noqa
-    bytes_string = str
-
 
 class BaseTrajectory(CxxPointer):
     def __init__(self, ptr):
@@ -156,9 +144,7 @@ def __init__(self, path, mode="r", format=""):
         super(Trajectory, self).__init__(ptr)
 
     def __repr__(self):
-        return "Trajectory('{}', '{}', '{}')".format(
-            self.path, self.__mode, self.__format
-        )
+        return f"Trajectory('{self.path}', '{self.__mode}', '{self.__format}')"
 
 
 class MemoryTrajectory(BaseTrajectory):
@@ -185,9 +171,9 @@ def __init__(self, data="", mode="r", format=""):
             )
 
         if mode == "r":
-            if isinstance(data, unicode_string):
+            if isinstance(data, str):
                 data = data.encode("utf8")
-            elif not isinstance(data, bytes_string):
+            elif not isinstance(data, bytes):
                 raise ChemfilesError("the 'data' parameter must be a string")
 
             ptr = self.ffi.chfl_trajectory_memory_reader(
@@ -196,14 +182,12 @@ def __init__(self, data="", mode="r", format=""):
         elif mode == "w":
             ptr = self.ffi.chfl_trajectory_memory_writer(format.encode("utf8"))
         else:
-            raise ChemfilesError(
-                "invalid mode '{}' passed to MemoryTrajectory".format(mode)
-            )
+            raise ChemfilesError(f"invalid mode '{mode}' passed to MemoryTrajectory")
 
         super(MemoryTrajectory, self).__init__(ptr)
 
     def __repr__(self):
-        return "MemoryTrajectory({}', '{}')".format(self.__mode, self.__format)
+        return f"MemoryTrajectory({self.__mode}', '{self.__format}')"
 
     def buffer(self):
         """
diff --git a/src/chemfiles/utils.py b/src/chemfiles/utils.py
index e0153524..59584194 100644
--- a/src/chemfiles/utils.py
+++ b/src/chemfiles/utils.py
@@ -1,17 +1,8 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
-import sys
 from ctypes import c_uint64, create_string_buffer
 
 from ._c_lib import _get_c_library
 from .misc import ChemfilesError, _last_error
 
-if sys.version_info >= (3, 0):
-    string_type = str
-else:
-    string_type = basestring
-
 
 class CxxPointer(object):
     # Used to prevent adding new attributes to chemfiles objects
@@ -41,7 +32,7 @@ def __del__(self):
     def __setattr__(self, key, value):
         if self.__frozen and not hasattr(self, key):
             raise TypeError(
-                "Can not add new attributes to this {}".format(self.__class__.__name__)
+                f"Can not add new attributes to this {self.__class__.__name__}"
             )
         object.__setattr__(self, key, value)
 
diff --git a/tests/_utils.py b/tests/_utils.py
index 1726ec64..546eaeee 100644
--- a/tests/_utils.py
+++ b/tests/_utils.py
@@ -1,5 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
 import chemfiles
 
 
diff --git a/tests/atom.py b/tests/atom.py
index 5953b49a..9013ac28 100644
--- a/tests/atom.py
+++ b/tests/atom.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import copy
 import unittest
 
diff --git a/tests/cell.py b/tests/cell.py
index 0dac1867..f85f2430 100644
--- a/tests/cell.py
+++ b/tests/cell.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import copy
 import unittest
 
diff --git a/tests/examples.py b/tests/examples.py
index ce2792e1..7f33b3fa 100644
--- a/tests/examples.py
+++ b/tests/examples.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import os
 import shutil
 import tempfile
diff --git a/tests/frame.py b/tests/frame.py
index 58a96996..4caa943b 100644
--- a/tests/frame.py
+++ b/tests/frame.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import copy
 import math
 import unittest
diff --git a/tests/misc.py b/tests/misc.py
index f97b9d56..0a6c1452 100644
--- a/tests/misc.py
+++ b/tests/misc.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import unittest
 import warnings
 
diff --git a/tests/property.py b/tests/property.py
index 4a128103..63be6dba 100644
--- a/tests/property.py
+++ b/tests/property.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import copy
 import unittest
 
diff --git a/tests/residue.py b/tests/residue.py
index c839e751..57ff8fec 100644
--- a/tests/residue.py
+++ b/tests/residue.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import copy
 import unittest
 
diff --git a/tests/selection.py b/tests/selection.py
index 7b70cbff..a890257a 100644
--- a/tests/selection.py
+++ b/tests/selection.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import copy
 import unittest
 
diff --git a/tests/topology.py b/tests/topology.py
index 5b85a9a2..60551cf5 100644
--- a/tests/topology.py
+++ b/tests/topology.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import copy
 import unittest
 
diff --git a/tests/trajectory.py b/tests/trajectory.py
index c2d3c718..f738b7d8 100644
--- a/tests/trajectory.py
+++ b/tests/trajectory.py
@@ -1,6 +1,3 @@
-# -*- coding=utf-8 -*-
-from __future__ import absolute_import, print_function, unicode_literals
-
 import os
 import unittest