old_contents: # Copyright (c) 2015, The MITRE Corporation. All rights reserved.
  # See LICENSE.txt for complete terms.
  
  """
  Compatibility library for mixbox.
  
  Only covers things that aren't already present in `six`.
  """
  
  from mixbox.vendor import six
  
  if six.PY2:
      long = long
      def xor(data, key):
          key = int(key)
          return b''.join([chr(ord(c) ^ key) for c in data])
  
      from collections import MutableSequence
  
  elif six.PY3:
      long = int
      def xor(data, key):
          key = int(key)
          b = bytearray(data)
          for i in range(len(b)):
              b[i] ^= key
          return bytes(b)
  
      from collections.abc import MutableSequence
  
new_contents: # Copyright (c) 2015, The MITRE Corporation. All rights reserved.
  # See LICENSE.txt for complete terms.
  
  """
  Compatibility library for mixbox.
  
  Only covers things that aren't already present in `six`.
  """
  
  from mixbox.vendor import six
  
  if six.PY2:
      long = long
      def xor(data, key):
          key = int(key)
          return b''.join([chr(ord(c) ^ key) for c in data])
  
      from collections import MutableSequence
      from collections import Sequence
  
  elif six.PY3:
      long = int
      def xor(data, key):
          key = int(key)
          b = bytearray(data)
          for i in range(len(b)):
              b[i] ^= key
          return bytes(b)
  
      from collections.abc import MutableSequence
      from collections.abc import Sequence
  
subject: add Sequence class to compat.py