#!/usr/bin/env python3

""" Fibonacci Module """

def fib(n):
   """ Calculates the n-th Fibonacci number """
   a, b = 0, 1
   for i in range(n):
       a, b = b, a+b
   return a

if __name__ == "__main__":
#    if fib(0) == 0 and fib(10) == 55 and fib(50) == 12586269025:
    if fib(0) == 0 and fib(10) == 55 and fib(15) == 610:
        print("fib() test OK")
    else:
        print("fib() test failed")