text: class Queue(object):
      
      def __init__(self):
          self.x = []
          
      def insert(self, e):
          if e not in self.x:
              self.x.append(e)
      
      def remove(self):
          try:
              p = self.x.pop(0)
              return p
          except:
              raise ValueError('not found')
          
  
  q = Queue()
  q.insert(7)
  q.insert(8)
  q.insert(9)
  print q.remove()