Following the docstring of matplotlib.dates, I tried the
> following commands, but failed. It says there is no argument
> needed when constructing PyDatetimeConverter object. If it
> is true, how about correcting it right away because the
> document is only one explaining its usage?
Early versions of the datetime converter supported time zones, but
there were problems in the implementation and I removed the feature.
The doc string was out of date.