官方例子无法生成json文件

[etcxy]

按官方给的例子，无法生成对应文件

datafaker file . out.txt 10 --meta meta.txt --format json
Traceback (most recent call last):
  File "/Users/etcxy/opt/miniconda3/envs/myenv37/lib/python3.7/site-packages/datafaker/cli.py", line 87, in main
    args = parse_args()
  File "/Users/etcxy/opt/miniconda3/envs/myenv37/lib/python3.7/site-packages/datafaker/cli.py", line 65, in parse_args
    raise ParamError('rdb not support for json format')
datafaker.exceptions.ParamError: rdb not support for json format

rdb not support for json format
(myenv37) ➜  /tmp