code: def itransform(self, seq):
          
          if self is not identity and self != identity:
              sa, sb, sc, sd, se, sf, _, _, _ = self
              for i, (x, y) in enumerate(seq):
                  seq[i] = (x * sa + y * sd + sc, x * sb + y * se + sf)
docs: Transform a sequence of points or vectors in place.
  
          :param seq: Mutable sequence of :class:`~planar.Vec2` to be
              transformed.
          :returns: None, the input sequence is mutated in place.