get rid of basestring and unicode (#115)

cython/core/abelian_group.pyx

@@ -47,14 +47,14 @@ cdef class AbelianGroup():
             except:
                 raise ValueError('Elementary divisors must be given '
                                  'as a sequence.')
-        int_types = [int, long]
+        int_types = [int]
         if _within_sage:
             int_types += [sage.rings.integer.Integer]
         for c in self.divisors:
             assert type(c) in int_types and c >= 0,\
                    'Elementary divisors must be non-negative integers.\n'
         for i in range(len(elementary_divisors) - 1):
-            n,m = elementary_divisors[i:i+2]
+            n, m = elementary_divisors[i:i+2]
             assert (n == m == 0) or (m % n == 0),\
                    'The elementary divisors must form a divisibility chain\n'
 

cython/core/basic.pyx

@@ -122,10 +122,6 @@ class MsgIO():
 msg_stream = MsgIO()
 
 
-# string testing for Python 3
-basestring = unicode = str
-
-
 def to_str(s):
     return s.decode()
 

cython/core/fundamental_group.pyx

@@ -71,9 +71,8 @@ cdef c_word_as_string(int *word, int num_generators, verbose_form):
 
 
 def word_as_list(word, int num_generators):
-    if not isinstance(word, basestring):
-        raise TypeError('Words must be represented '
-                        'as Python strings.')
+    if not isinstance(word, str):
+        raise TypeError('Words must be represented as Python strings.')
     word_list = []
     if num_generators > 26:
         for prefix, number in re.findall(r'([xX])(\d+)', word):

cython/core/triangulation.pyx

@@ -95,9 +95,8 @@ cdef class Triangulation():
                 spec = getattr(spec, attr)()
                 break
         if spec is not None and spec != 'empty':
-            # basestring was removed from python3 but cython supports it for all pythons
-            if not isinstance(spec, (basestring, bytes)):
-                raise TypeError(triangulation_help%
+            if not isinstance(spec, (str, bytes)):
+                raise TypeError(triangulation_help %
                                 self.__class__.__name__)
             self.get_triangulation(spec, remove_finite_vertices)
             if self.c_triangulation == NULL:

twister/lib/main.py

@@ -8,12 +8,6 @@
 from plink import LinkManager
 from .twister_core import build_bundle, build_splitting, twister_version
 
-# Python 3 compatibility
-try:
-	basestring
-except NameError:  # Python 3
-	basestring = unicode = str
-
 surface_database_path = os.path.join(os.path.dirname(__file__), 'surfaces')
 surface_database = set(os.listdir(surface_database_path))
 version = twister_version()
@@ -22,7 +16,7 @@ def _get_surface(surface):
 	if isinstance(surface, tuple) and len(surface) == 2 and isinstance(surface[0], int) and isinstance(surface[1], int):
 		return LP_surface(surface[0], surface[1])
 
-	if isinstance(surface, basestring):
+	if isinstance(surface, str):
 		# If surface is actually the contents of a surface file.
 		if surface.startswith('# A Twister surface file'):
 			return surface