'Context manager to facilitate writing the movie file.
``*args, **kw`` are any parameters that should be passed to `setup`.'

@contextlib.contextmanager
def saving(self, fig, outfile, dpi, *args, **kwargs):

    self.setup(fig, outfile, dpi, *args, **kwargs)
    try:
        (yield self)
    finally:
        self.finish()
