'Retrieve the action callable.
This internal method is used to retrieve the callable
implementing the action.  If ``real_action`` was specified as
``None`` or one of the standard string names, an internal
method of the ``argparse.ArgumentParser`` instance is used to
resolve it into an actual action class, which is then
instantiated.  This is cached, in case the action is called
multiple times.
:param parser: The ``argparse.ArgumentParser`` instance.
:returns: The action callable.'

def _get_action(self, parser):

    if (self.real_action_args is not False):
        (option_strings, dest, help, kwargs) = self.real_action_args
        action_class = parser._registry_get('action', self.real_action)
        if (action_class is None):
            print((_('WARNING:    Programming    error:    Unknown    real    action    "%s"') % self.real_action), file=sys.stderr)
            self.real_action = None
        else:
            self.real_action = action_class(option_strings, dest, help=help, **kwargs)
        self.real_action_args = False
    return self.real_action
