Get model configuration file name from argv

def get_config_file():
    # type: () -> AnyStr
    """Get model configuration file name from argv"""
    parser = argparse.ArgumentParser(description="Read configuration file.")
    parser.add_argument('-ini', help="Full path of configuration file")
    args = parser.parse_args()
    ini_file = args.ini
    if not FileClass.is_file_exists(ini_file):
        print("Usage: -ini <full path to the configuration file.>")
        exit(-1)
    return ini_file