'Given a lambda_name and stage_name, return a valid API URL.'

def get_api_url(self, lambda_name, stage_name):

    api_id = self.get_api_id(lambda_name)
    if api_id:
        return 'https://{}.execute-api.{}.amazonaws.com/{}'.format(api_id, self.boto_session.region_name, stage_name)
    else:
        return None
