new_contents: class Queue:
      # initialize your data structure here.
      def __init__(self):
          self.instack = []
          self.outstack = []
          self.insize = 0
          self.outsize = 0
          
      # @param x, an integer
      # @return nothing
      def push(self, x):
          self.instack.append(x)
          self.insize += 1
          
      # @return nothing
      def pop(self):
          while self.insize > 1:
              top = self.instack.pop()
              self.outstack.append(top)
              self.insize -= 1
              self.outsize += 1
          if self.insize == 1:
              self.instack.pop()
              self.insize -= 1
              while self.outsize > 0:
                  top = self.outstack.pop()
                  self.instack.append(top)
                  self.insize += 1
                  self.outsize -= 1
                  
      # @return an integer
      def peek(self):
          while self.insize > 1:
              top = self.instack.pop()
              self.outstack.append(top)
              self.insize -= 1
              self.outsize += 1
          if self.insize == 1:
              res = self.instack[-1]
              while self.outsize > 0:
                  top = self.outstack.pop()
                  self.instack.append(top)
                  self.insize += 1
                  self.outsize -= 1
              return res
              
      # @return an boolean
      def empty(self):
          return self.insize == 0
  
subject: Create ImpQueueByStacks_001.py