code: def qteRegisterApplet(self, cls, replaceApplet: bool=False):
          if not issubclass(cls, QtmacsApplet):
              args = ('cls', 'class QtmacsApplet', inspect.stack()[0][3])
              raise QtmacsArgumentError(*args)
          class_name = cls.__name__
          if class_name in self._qteRegistryApplets:
              msg = 'The original applet <b>{}</b>'.format(class_name)
              if replaceApplet:
                  msg += ' was redefined.'
                  self.qteLogger.warning(msg)
              else:
                  msg += ' was not redefined.'
                  self.qteLogger.warning(msg)
                  return class_name
          cls.__qteRegisterAppletInit__()
          self._qteRegistryApplets[class_name] = cls
          self.qteLogger.info('Applet <b>{}</b> now registered.'
                              .format(class_name))
          return class_name