def twinx(self):
ax2 = self.figure.add_axes(self.get_position(True), sharex=self,<EOL>frameon=False)<EOL>ax2.yaxis.tick_right()<EOL>ax2.yaxis.set_label_position('<STR_LIT:right>')<EOL>self.yaxis.tick_left()<EOL>return ax2<EOL>
call signature::

  ax = twinx()

create a twin of Axes for generating a plot with a sharex
x-axis but independent y axis.  The y-axis of self will have
ticks on left and the returned axes will have ticks on the
right