old_contents: # -*- coding: utf-8 -*-
  # This file is part of beets.
  # Copyright 2016, Adrian Sampson.
  #
  # Permission is hereby granted, free of charge, to any person obtaining
  # a copy of this software and associated documentation files (the
  # "Software"), to deal in the Software without restriction, including
  # without limitation the rights to use, copy, modify, merge, publish,
  # distribute, sublicense, and/or sell copies of the Software, and to
  # permit persons to whom the Software is furnished to do so, subject to
  # the following conditions:
  #
  # The above copyright notice and this permission notice shall be
  # included in all copies or substantial portions of the Software.
  """Custom collections classes
  """
  
  
  class IdentityFallbackDict(dict):
      """A dictionary which is "transparent" (maps keys to themselves) for all
      keys not in it.
      """
      def __getitem__(self, key):
          try:
              return dict.__getitem__(self, key)
          except KeyError:
              return key
  
new_contents: # -*- coding: utf-8 -*-
  # This file is part of beets.
  # Copyright 2016, Adrian Sampson.
  #
  # Permission is hereby granted, free of charge, to any person obtaining
  # a copy of this software and associated documentation files (the
  # "Software"), to deal in the Software without restriction, including
  # without limitation the rights to use, copy, modify, merge, publish,
  # distribute, sublicense, and/or sell copies of the Software, and to
  # permit persons to whom the Software is furnished to do so, subject to
  # the following conditions:
  #
  # The above copyright notice and this permission notice shall be
  # included in all copies or substantial portions of the Software.
  
  """Custom collections classes.
  """
  
  from __future__ import division, absolute_import, print_function
  
  
  class IdentityFallbackDict(dict):
      """A dictionary which is "transparent" (maps keys to themselves) for all
      keys not in it.
      """
      def __getitem__(self, key):
          try:
              return dict.__getitem__(self, key)
          except KeyError:
              return key
  
subject: Add __future__ imports to a new module