python queue basic definition and usage [initialization, assignment, judgment, etc.]

# -*- coding:utf-8 -*-
#! python3
class Node(object):   # node, which includes two attributes, a value for the node and a point to where the node will be next
  def __init__(self,value):
     = value  The value of the # node
     = None   # node's next pointing to
class Queue(object):    #The class Queue
  def __init__(self):   # Initialize this queue
     = None   The nodes pointed to by the head and tail of the # queue are None, initialize the
     = None
  def enter(self,n):
    packNode = Node(n)   # Create a new node instance of Node with value n
    if  == None: # If the first pointer is empty
       = packNode    # Assign the node pointed to by the head to the node passed in
       =    # and assign the node pointed to by the tail to
    else:
       = packNode    # If the queue is not empty, assign the new node to the next position in the current last
       = packNode      # Then move last to point to the node you just added.
  def quit(self):
    if  == None:
      return None
    else:
      tmp =      # If a value exists in the queue, assign the first value in the queue to tmp
       =   # Change first's pointing to next to first pointing to
      return tmp
if __name__ == '__main__':
  print("------------ queue starts --------")
  q = Queue()
  # n1 = Node(1)
  # n2 = Node(2)
  # n3 = Node(3)
  (1)
  (2)
  (3)
  print(())
  print(())
  print(())
  # print(q)