DOC: docstrings of is_type_factory and is_instance_factory in config.py not accurate.

[fumitoh]

The validators returned by the functions don't return True, contrary to the docstrings' descriptions.

[jreback]

@fumitoh exactly what are you referring?

[fumitoh]

here and here

Both inner s return None.

[jreback]

but how is this incorrect?
the doc string says it's returning a function which it is; not the result of the function

[fumitoh]

The doc string says:

Returns
-------
validator - a function of a single argument x , which returns the
            True if type(x) is equal to `_type`

The validator does not return True. It's just for raising an error when invalid type objects are passed.

[jreback]

ok if you'd like to do a PR to fix would be fine