code: def prepareToRemove(self):
          
          # disconnect the signals from the input and output nodes
          for node in (self._outputNode, self._inputNode):
              self.disconnectSignals(node)
  
          # clear the pointers to the nodes
          self._inputNode = None
          self._outputNode = None
  
          return True
docs: Handles any code that needs to run to cleanup the connection \
          before it gets removed from the scene.
          
          :return     <bool> success