docs: def get_deploy_hosts_list(cwd, key=None, file="propel.yml"):
      """
      Returns the remote hosts in propel
      :param cwd:
      :param key:
      :param file:
      :return: list
      """
      config = propel_deploy_config(cwd=cwd, file=file)["hosts"]
      return config[key] if key else [v for k, l in config.items() for v in l]