class_docstr: Turn any callable (which takes a cli and returns a boolean) into a Filter.
  
  This can be used as a decorator::
  
      @Condition
      def feature_is_active(cli):  # `feature_is_active` becomes a Filter.
          return True
  
  :param func: Callable which takes either a
      :class:`~prompt_toolkit.interface.CommandLineInterface` or nothing and
      returns a boolean. (Depending on what it takes, this will become a
      :class:`.Filter` or :class:`~prompt_toolkit.filters.CLIFilter`.)
code: def test_args(self, *a):
      return test_callable_args(self.func, a)
  
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 Condition obj's underlying member method code with example usage: obj.test_args() and returns: test_callable_args