A structured input, preferably a pandas.DataFrame, but in
principle accepts anything that can be converted into it.
Kwargs:
subplots (None, True, or False; default=None)
Whether you want to split data into subplots or not. If True,
the top level is treated as a subplot. If None, detects
automatically based on agg.columns.names – the first entry
to start with subplots. will be used. This is the default
output from stats.aggregate and is recommended.