def METHOD_NAME():
    '''Return the valid access types for the GOcean API. Reads the values
    from the config file the first time the method is called.
    :returns: valid access types for the GOcean API.
    :rtype: list[str]
    '''
    if not GOceanConstants._VALID_ACCESS_TYPES:
        conf = Config.get().api_conf("gocean1.0")
        GOceanConstants._VALID_ACCESS_TYPES = \
            list(conf.get_access_mapping().keys())
    return GOceanConstants._VALID_ACCESS_TYPES