def grab_frame(self):
    """
    Grab the image information from the figure and save as a movie frame.
    """
verbose.report('MovieWriter.grab_frame: Grabbing frame.', level='debug')
try:
    self.fig.savefig(self._frame_sink(), format=self.frame_format, dpi=self.dpi
        )
except RuntimeError:
    out, err = self._proc.communicate()
verbose.report("""MovieWriter -- Error running proc:
%s
%s""" % (out, err),
    level='helpful')
raise
Matplotlib.animation: how to remove white margin