class Queue(object):
    def __init__(self):
        """ Initialise empty Queue list."""
        self.li = []

    def insert(self,item):
        """ Add item to back of Queue."""
        self.li.append(item)

    def remove(self):
        """ Check if items in the Queue list.
            If True, remove the first item.
            Else, return 'empty queue.'"""
        if self.li:
            return self.li.pop(0)
        return 'empty queue'

queue = Queue()
queue.insert(5)
queue.insert(6)
print queue.remove()
queue.insert(7)
print queue.remove()
print queue.remove()
print queue.remove()