code: def register(self, *handlers, **params):
          
          for handler in handlers:
  
              if issubclass(handler, PWModel):
                  handler = type(
                      handler._meta.db_table.title() + 'Admin',
                      (PWAdminHandler,), dict(model=handler, **params))
                  self.app.register(handler)
                  continue
  
              name = handler.name.lower()
              self.handlers[name] = handler
docs: Ensure that handler is not registered.