code: def system_listMethods(self):
          
  
          methods = set(self.funcs.keys())
          if self.instance is not None:
              # Instance can implement _listMethod to return a list of
              # methods
              if hasattr(self.instance, '_listMethods'):
                  methods |= set(self.instance._listMethods())
              # if the instance has a _dispatch method then we
              # don't have enough information to provide a list
              # of methods
              elif not hasattr(self.instance, '_dispatch'):
                  methods |= set(list_public_methods(self.instance))
          return sorted(methods)
docs: system.listMethods() => ['add', 'subtract', 'multiple']
  
          Returns a list of the methods supported by the server.