class_docstr: Filter to activate/deactivate a feature, depending on a condition.
  The return value of ``__call__`` will tell if the feature should be active.
docstr: Inverting of filters using the ~ operator.
docstr_tok: ["Inverting","of","filters","using","the","~","operator","."]
code: def __invert__(self):
      """
      Inverting of filters using the ~ operator.
      """
      return _invert_cache[self]
  
imports: from __future__ import unicode_literals
  from abc import ABCMeta, abstractmethod
  from six import with_metaclass
  from prompt_toolkit.utils import test_callable_args
label_desc: Use image node_id 4 for calling the Filter obj's underlying member method code with example usage: obj.__invert__() and returns: _invert_cache