获取文件内容并返回, 如果文件不存在, 则返回 rt

    :param pth:
    :type pth:
    :param rt: ``如果需要指定返回值, 请设置该值``
    :type rt:
    :return:
    :rtype:

def pickle_f2m(pth, rt=None):
    """
        获取文件内容并返回, 如果文件不存在, 则返回 rt

    :param pth:
    :type pth:
    :param rt: ``如果需要指定返回值, 请设置该值``
    :type rt:
    :return:
    :rtype:
    """
    r = rt
    try:
        with open(pth, 'rb') as f:
            r = pickle.load(f)
    except Exception as err:
        sys.stderr.write('pickle_f2m(pth={}) with error: {}\n'.format(pth, err))
    return r