def get_valid_base_urls(order=None):
    """
    Return a list of valid base URLs from where the user analysis transform may be downloaded from.
    If order is defined, return given item first.
    E.g. order=http://atlpan.web.cern.ch/atlpan -> ['http://atlpan.web.cern.ch/atlpan', ...]
    NOTE: the URL list may be out of date.

    :param order: order (string).
    :return: valid base URLs (list).
    """

    valid_base_urls = []
    _valid_base_urls = ["http://www.usatlas.bnl.gov",
                        "https://www.usatlas.bnl.gov",
                        "http://pandaserver.cern.ch",
                        "http://atlpan.web.cern.ch/atlpan",
                        "https://atlpan.web.cern.ch/atlpan",
                        "http://classis01.roma1.infn.it",
                        "http://atlas-install.roma1.infn.it"]

    if order:
        valid_base_urls.append(order)
        for url in _valid_base_urls:
            if url != order:
                valid_base_urls.append(url)
    else:
        valid_base_urls = _valid_base_urls

    return valid_base_urls