# DequeModule.py
#!/usr/bin/python3
class Deque(object):
    def __init__(self):
        self.items = []

    def isEmpty(self):
        return len(self.items) == 0

    def addFront(self, v):
        try:
            self.items.append(v)
            return True
        except Exception as err:
            return False

    def addRear(self, v):
        try:
            self.items.insert(0, v)
            return True
        except Exception as err:
            return False

    def removeFront(self):
        try:
            return self.items.pop()
        except Exception as err:
            return None

    def removeRear(self):
        try:
            return self.items.pop(0)
        except Exception as err:
            return None

    def size(self):
        return len(self.items)

    def __str__(self):
        s = 'rear ->'

        output = []

        for item in self.items:
            output.append(str(item))

        s += '->'.join(output)

        s += '-> front'

        return s
            

#!/usr/bin/python3
from DequeModule import Deque

def main():
    d = Deque()

    print(d.isEmpty()) # True

    d.addRear(4)
    d.addRear('dog')
    d.addFront('cat')
    d.addFront(True)

    print(d) # rear ->dog->4->cat->True-> front

    print(d.size()) # 4
    print(d.isEmpty()) # False

    d.addRear(8.4)
    print(d.removeRear()) # 8.4
    print(d.removeFront()) # True

    print(d) # rear ->dog->4->cat-> front

if __name__ == '__main__':
    main()