new_contents: # ~*~ coding: utf-8 ~*~
  """
  missing.py
  ~~~~~~~~~~~~~~~
  
  This module defines a reliable sentinel value that can be used as a default
  value, especially when ``None``, ``True``, and ``False`` can be a valid values
  for the function.
  
  """
  
  from werkzeug.datastructures import ImmutableDict
  
  
  # @TODO Make this work as an empty iterator?
  class MissingSentinel(object):
  
      """This class can be used to create an object that can be used as
      a flexible sentinel value. These can be very useful for default keyword
      arguments that can be boolean values and you want to test `None`. They can
      also be used like a boolean in an `if` statement, as this object will
      always evaluate to `False` when cast to a boolean.
  
      >>> MISSING = MissingSentinel()
      >>> bool(MISSING) is False
      True
      >>> False is not MISSING
      True
      >>> print("success") if not MISSING else print("failure")
      "success"
  
      """
  
      def __bool__(self) -> bool:
          """Define the boolean value for this object.
  
          This method in Python 3.x is used in boolean expressions to determine
          the truthy value of the variable. Since this class represents that
          something is missing, it stands to reason that it should evaluate to
          ``False``. It is aliased to ``__nonzero__`` for Python 2.
          """
          return False
  
      def __len__(self) -> int:
          """Define the length of this instance, which will always be 0."""
          return 0
  
  
  class MissingDictSentinel(MissingSentinel, ImmutableDict):
      """This class can be used to create an object that works as sentinel, but
      behaves like a dictionary. This is still very useful for dealing with
      default arguments, but it might make more sense as a default value than the
      standard :class:`MissingSentinel`.
  Just like the :class:`MissingSentinel`, this evaluates to ``False`` when
      cast to a bool.
  
      >>> MISSING_DICT = MissingDictSentinel()
      >>> bool(MISSING_DICT) is False
      True
      >>> False is not MISSING_DICT
      True
      >>> print("success") if not MISSING_DICT else print("failure")
      "success"
  
      """
  
  
  MISSING = MissingSentinel()
  MISSINGDICTSENTINEL = MissingDictSentinel()
  
subject: Update app/helpers/missing.py