python 实现尾递归斐波那契数列

def (a, b, n):
    if n == 0:
        return a
    return fibonacci(b, a + b, n - 1)

if __name__ == '__main__':
    while True:
        n = None
        try:
            n = input('>> ')
        except EOFError:
            exit()
        print(fibonacci(0, 1, int(n)))

fib = lambda n, x=0, y=1: x if not n else fib(n-1, y, x+y)
print("lambda:" + str(fib(int(n))))