code: def add(self, pane):
          
          if isinstance(pane, list):
              initialised_panes = []
              for p in pane:
                  initialised_panes.append(self.init_pane(p))
              self.panes.append(initialised_panes)
          else:    
              pane = self.init_pane(pane)
              self.panes.append(pane)
docs: Adds new panes to the window