class Queue:
    # Circular List Implementation

    DEFAULT_CAPACITY = 10

    def __init__(self):
    # instance variables: _data, _size, _front
        self._data = [None]*Queue.DEFAULT_CAPACITY
        self._front = 0
        self._size = 0

    def __str__(self):
    # string representation of queue
        pass

    def __len__(self):
    # return length of queue
        return self._size
    
    def is_empty(self):
    # return True if queue is empty otherwise return False
        return self._size == 0
    
    def first(self):
    # return first item of queue if it is not empty; otherwise return None
        if self._size == 0:
            return None
        else:
            self._data[self._front]

    
    
    def dequeue(self):
    # remove and return first item in queue; return None if queue is empty

    def enqueue(self,e):
    # add item e to the end of queue. If list is full, resize the list by
    # creating a new list of twice the size and moving items from old list 
    # to new list; Do not forget to adjust _size and _front

    def _resize(self,cap):
    # method to resize

["ha"]*9

['ha', 'ha', 'ha', 'ha', 'ha', 'ha', 'ha', 'ha', 'ha']

[None]*10

[None, None, None, None, None, None, None, None, None, None]