def _format_nics(nics):
    """ Create a networks data structure for python-novaclient.


    **Note** "auto" is the safest default to pass to novaclient

    :param nics: either None, one of strings "auto" or "none"or string with a
    comma-separated list of nic IDs from OpenStack.
    :return: A data structure that can be passed as Nics
    """
    if not nics:
        return "auto"
    if nics == "none":
        return "none"
    if nics.lower() == "auto":
        return "auto"
    return [{"net-id": item, "v4-fixed-ip": ""}
            for item in nics.strip().split(",")]