code: def open_gif(self, filename):
          
          if filename[-3:] != 'gif':
              raise Exception('Unsupported filetype.  Must end in .gif')
          if isinstance(vtki.FIGURE_PATH, str) and not os.path.isabs(filename):
              filename = os.path.join(vtki.FIGURE_PATH, filename)
          self._gif_filename = os.path.abspath(filename)
          self.mwriter = imageio.get_writer(filename, mode='I')
docs: Open a gif file.
  
          Parameters
          ----------
          filename : str
              Filename of the gif to open.  Filename must end in gif.