code: def add(self, items):
          '''add a submenu'''
          if not isinstance(items, list):
              items = [items]
          for m in items:
              updated = False
              for i in range(len(self.items)):
                  if self.items[i].name == m.name:
                      self.items[i] = m
                      updated = True
              if not updated:
                  self.items.append(mf add(self, items):
          '''add a submenu'''
          if not isinstance(items, list):
              items = [items]
          for m in items:
              updated = False
              for i in range(len(self.items)):
                  if self.items[i].name == m.name:
                      self.items[i] = m
                      updated = True
              if not updated:
                  self.items.append(m)
docs: add a submenu