def twinx(ax=None):
if ax is None:<EOL><INDENT>ax=gca()<EOL><DEDENT>ax1 = ax.twinx()<EOL>draw_if_interactive()<EOL>return ax1<EOL>
Make a second axes overlay *ax* (or the current axes if *ax* is
*None*) sharing the xaxis.  The ticks for *ax2* will be placed on
the right, and the *ax2* instance is returned.

.. seealso::
   :file:`examples/api_examples/two_scales.py`