code: def get_mime_data(self, mime_type):
          
          buffer_address = ffi.new('unsigned char **')
          buffer_length = ffi.new('unsigned long *')
          mime_type = ffi.new('char[]', mime_type.encode('utf8'))
          cairo.cairo_surface_get_mime_data(
              self._pointer, mime_type, buffer_address, buffer_length)
          return (ffi.buffer(buffer_address[0], buffer_length[0])
                  if buffer_address[0] != ffi.NULL else None)
docs: Return mime data previously attached to surface
          using the specified mime type.
  
          :param mime_type: The MIME type of the image data.
          :type mime_type: ASCII string
          :returns:
              A CFFI buffer object, or :obj:`None`
              if no data has been attached with the given mime type.
  
          *New in cairo 1.10.*