Some [source] links in the documentation point to _decorators.py
In the Pandas documentation pages, some [source] links of the functions don't point to the actual implementation of the function, but to `pandas/util/_decorators.py`, presumably because some of the decorators there have been used on the function in question and this messes up the doc generation somehow.

For an example, see the documentation of [DataFrame.astype](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.astype.html). I'm not sure if this is a systematic problem or if it applies to just this one case.