code: def add_input_nodes(self, input_nodes):
          
          self.input_queues = [queue.Queue(maxsize=3) for _ in input_nodes]
          for input_node, input_queue in zip(input_nodes, self.input_queues):
              input_node.add_output_queue(input_queue)
docs: Set the given nodes as inputs for this node.
  
          Creates a limited-size queue.Queue for each input node and
          registers each queue as an output of its corresponding node.