flatten_json() missing 1 required positional argument: 'json'#56

I'm getting the error "flatten_json() missing 1 required positional argument: 'json'" when using it with one json argument like in the docs: `flatten_json(json)` Edit: It looks like the documentation should be updated, since now the code reads: ``` def flatten_json( form, json, parent_key='', separator='-', skip_unknown_keys=True ): ```