def METHOD_NAME(self, form, choice_form):
    """
    Called if a form is invalid. Re-renders the context data with the data-filled
    forms and errors.
    Args:
        form: Poll Form
        choice_form: Choice Form
    """
    return self.render_to_response(
        self.get_context_data(form=form, choice_form=choice_form)
    )