code: def set_axes(self, channels, ax):
          
          # To make sure displayed as hist
          if len(set(channels)) == 1:
              channels = channels[0],
  
          self.current_channels = channels
          # Remove existing gates
          for gate in self.gates:
              gate.remove_spawned_gates()
          ## 
          # Has a clear axis command inside!!
          # which will "force kill" spawned gates
          self.plot_data()
  
          for gate in self.gates:
              sgate = gate.spawn(channels, ax)
              gate._refresh_activation()
docs: channels : iterable of string
              each value corresponds to a channel names
              names must be unique