Returns the remote hosts in propel
    :param cwd:
    :param key:
    :param file:
    :return: list

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]