fifo queue in python

fifo.py

class Fifo:
    def __init__(self, size):
        self.size = size
        self.count = 0
        self.q = [None] * size
        self.head = 0
        self.tail = 0

    def push(self, elm):
        print self.count
        print self.size
        if (self.count == self.size):
            print 'double!'
            new_q = [None] * self.size * 2
            for x in range(self.size):
                new_q[x] = self.pop()
            self.head = self.size
            self.count = self.size
            self.tail = 0
            self.size = self.size * 2
            self.q = new_q

        self.q[self.head] = elm
        self.head = (self.head + 1) % self.size
        self.count = self.count + 1
        print self.q

    def pop(self):
        elm = self.q[self.tail]
        self.q[self.tail] = None
        self.tail = (self.tail + 1) % self.size
        self.count = self.count - 1
        return elm


q = Fifo(4)
for i in range(10):
    q.push(i)