#coding:utf-8

class DoubleDeque(object):
    def __init__(self):
        self.items=[]
    def isEmpty(self):
        return self.items==[]
    def addFront(self,item):
        self.items.append(item)
    def addRear(self,item):
        self.items.insert(0,item)
    def removeFront(self):
        return self.items.pop()
    def removeRear(self):
        return self.items.pop(0)
    def size(self):
        return len(self.items)

def palchecker(astring):
    chardeque = DoubleDeque()
    for ch in astring:
        chardeque.addRear(ch)
    stillEqual=True
    while chardeque.size()>1 and stillEqual:
        first= chardeque.removeFront()
        last = chardeque.removeRear()
        if first != last:
            stillEqual=False
            break
    return stillEqual
print(palchecker("abba"))
