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: The actual call to evaluate the filter.
docstr_tok: ["The","actual","call","to","evaluate","the","filter","."]
code: def __call__(self, *a, **kw):
      """
      The actual call to evaluate the filter.
      """
      return True
  
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 1 for calling the Filter obj's underlying member method code with example usage: obj.__call__() and returns: True