def set_param(log_level=None, data_dir=None):
    """
    Set mobileDNA parameters.

    :param log_level: new value for log level
    :param data_dir: new data directory
    """
    global LOG_LEVEL
    global DATA_DIR
    if log_level:
        LOG_LEVEL = log_level
    if data_dir:
        DATA_DIR = data_dir
