old_contents: # compatibility module for different python versions
  import sys
  
  if sys.version_info[:2] > (3, 0):
  
      PY2 = False
      PY3 = True
  
      Bytes = bytes
      Unicode = str
      basestring = str
  
      class_type_name = 'class'
      ClassType = type
      exception_module = 'builtins'
      new_class = type
      self_name = '__self__'
      from io import StringIO
      xrange = range
      
  else:
      
      PY2 = True
      PY3 = False
      
      Bytes = str
      Unicode = unicode
      basestring = basestring
      
      class_type_name = 'type'
      from types import ClassType
      exception_module = 'exceptions'
      from new import classobj as new_class
      self_name = 'im_self'
      from cStringIO import StringIO
      xrange = xrange
  
  try:
      from mock import call as mock_call
  except ImportError: # pragma: no cover
      class MockCall: pass
      mock_call = MockCall()
  
  try:
      from unittest.mock import call as unittest_mock_call
  except ImportError: 
      class UnittestMockCall: pass
      unittest_mock_call = UnittestMockCall()
  
new_contents: # compatibility module for different python versions
  import sys
  
  if sys.version_info[:2] > (3, 0):
  
      PY2 = False
      PY3 = True
  
      Bytes = bytes
      Unicode = str
      basestring = str
      BytesLiteral = lambda x: x.encode('latin1')
      UnicodeLiteral = lambda x: x
  
      class_type_name = 'class'
      ClassType = type
      exception_module = 'builtins'
      new_class = type
      self_name = '__self__'
      from io import StringIO
      xrange = range
      
  else:
      
      PY2 = True
      PY3 = False
      
      Bytes = str
      Unicode = unicode
      basestring = basestring
      BytesLiteral = lambda x: x
      UnicodeLiteral = lambda x: x.decode('latin1')
      
      class_type_name = 'type'
      from types import ClassType
      exception_module = 'exceptions'
      from new import classobj as new_class
      self_name = 'im_self'
      from cStringIO import StringIO
      xrange = xrange
  
  try:
      from mock import call as mock_call
  except ImportError: # pragma: no cover
      class MockCall: pass
      mock_call = MockCall()
  
  try:
      from unittest.mock import call as unittest_mock_call
  except ImportError: 
      class UnittestMockCall: pass
      unittest_mock_call = UnittestMockCall()
  
subject: Add Python version agnostic helpers for creating byte and unicode literals.