code: def _l2rgb(self, mode):
          
          self._check_modes(("L", "LA"))
          self.channels.append(self.channels[0].copy())
          self.channels.append(self.channels[0].copy())
          if self.fill_value is not None:
              self.fill_value = self.fill_value[:1] * 3 + self.fill_value[1:]
          if self.mode == "LA":
              self.channels[1], self.channels[3] = \
                  self.channels[3], self.channels[1]
          self.mode = mode
docs: Convert from L (black and white) to RGB.