code: def with_known_args(self, **kwargs):
      
      argspec = inspect.getargspec(self.func)
      stored = {}
      for key, arg in six.iteritems(kwargs):
        if key in argspec.args or argspec.keywords:
          stored[key] = arg
      if stored:
        return self.with_args(**stored)
      return self
docs: Send only known keyword-arguments to the phase when called.