code: def add_type_conversion(self, start_type, target_type, conversion_function):
          
          self.registered_color_spaces.add(start_type)
          self.registered_color_spaces.add(target_type)
          logger.debug(
              'Registered conversion from %s to %s', start_type, target_type)
docs: Register a conversion function between two color spaces.
          :param start_type: Starting color space.
          :param target_type: Target color space.
          :param conversion_function: Conversion function.