old_contents: from __future__ import print_function
  from __future__ import absolute_import
  from __future__ import division
  
  # import abc
  import functools
  
  
  __all__ = ['memoize']
  
  
  class abstractstatic(staticmethod):
      """Decorator for declaring a static method abstract.
  
      Parameters
      ----------
      function : callable
          The method to declare abstract static.
      """
  
      __slots__ = ()
  
      def __init__(self, function):
          super(abstractstatic, self).__init__(function)
          function.__isabstractmethod__ = True
  
      __isabstractmethod__ = True
  
  
  def memoize(func, *args, **kwargs):
      """Decorator to wrap a function with a memoizing callable.
  
      Parameters
      ----------
      func : callable
          The function that should be memoized.
      """
      cache = func.cache = {}
  
      @functools.wraps(func)
      def memoized_func(*args, **kwargs):
          key = str(args) + str(kwargs)
          if key not in cache:
              cache[key] = func(*args, **kwargs)
          return cache[key]
  
      return memoized_func
  
  
  # ==============================================================================
  # Main
  # ==============================================================================
  
  if __name__ == "__main__":
      pass
  
new_contents: from __future__ import print_function
  from __future__ import absolute_import
  from __future__ import division
  
  # import abc
  import functools
  
  
  __all__ = [
      'abstractstatic',
      'abstractclassmethod',
      'memoize'
  ]
  
  
  class abstractstatic(staticmethod):
      """Decorator for declaring a static method abstract.
  
      Parameters
      ----------
      function : callable
          The method to declare abstract static.
      """
  
      __slots__ = ()
  
      __isabstractmethod__ = True
  
      def __init__(self, function):
          function.__isabstractmethod__ = True
          super(abstractstatic, self).__init__(function)
  
  
  class abstractclassmethod(classmethod):
      """Decorator for declaring a class method abstract.
  
      Parameters
      ----------
      function : callable
          The class method to declare abstract.
      """
  
      __slots__ = ()
  
      __isabstractmethod__ = True
  
      def __init__(self, function):
          function.__isabstractmethod__ = True
          super(abstractclassmethod, self).__init__(function)
  
  
  def memoize(func, *args, **kwargs):
      """Decorator to wrap a function with a memoizing callable.
  
      Parameters
      ----------
      func : callable
          The function that should be memoized.
      """
      cache = func.cache = {}
  
      @functools.wraps(func)
      def memoized_func(*args, **kwargs):
          key = str(args) + str(kwargs)
          if key not in cache:
              cache[key] = func(*args, **kwargs)
          return cache[key]
  
      return memoized_func
  
  
  # ==============================================================================
  # Main
  # ==============================================================================
  
  if __name__ == "__main__":
      pass
  
subject: add abstractclassmethod for py27 compat