Class implementation

class Queue:
    # Constructor, which creates a new empty queue:
    def __init__(self):
        self.__items=[]
        
    # Adds a new item to the back of the queue, and returns nothing:
    def queue(self, item):
        self.items.append(item)
        
    # Removes and returns the front-most item in the queue.  
    # Returns nothing if the queue is empty.
    def dequeue(self):
        return self.__items.pop()
    
    # Returns the front-most item in the queue, and DOES NOT change the queue.  
    def peek(self):
        return self.__items[len(self.__items)-1]
        
    # Returns True if the queue is empty, and False otherwise:
    def is_empty(self):
        return len(self.__items) == 0
    
    # Returns the number of items in the queue:
    def size(self):
        return len(self.__items)
    
    # Removes all items from thq queue, and sets the size to 0:
    def clear(self):
        self.__items.pop()
        return len(self.__items) == 0
    
    # Returns a string representation of the queue
    def __str__(self):
        # TODO: You must implement this method!