class_queue

class queue:
    def __init__(self):
        self.que = []
    def insert(self,item):
    #@param:
    #   item: any;
        self.que.append(item)
    def out(self):
        assert self.que!=[], "Queue is empty"
        self.que = self.que[1:]
    def first(self):
    #return: first item in queue;
        assert self.que!=[], "Queue is empty"
        return(self.que[0])
    def last(self):
    #return: last item in queue;
        assert self.que!=[], "Queue is empty"
        return(self.que[len(self.que)-1])
    def empty(self):
    #@return: bool;
        if self.que==[]: return(True)
        else: return(False)