def METHOD_NAME():
    """Check that the ``CRDS_SERVER_URL`` environment variable is set.
    This controls where Mirage will look for CRDS information. If the
    env variable is not set, set it to the JWST CRDS server.
    """
    crds_server = os.environ.get('CRDS_SERVER_URL')
    if crds_server is None:
        os.environ["CRDS_SERVER_URL"] = "https://jwst-crds.stsci.edu"