Three different ways to compute fibonacci

fib.py

#!/usr/bin/env python

def fib_iterative(n):
    a,b = 1,1
    for i in range(n - 1):
        a,b = b,a+b
    return a 

def fib_recursive(n):
    if (n == 1 or n == 2 ):
        return 1
    else:
        return fib_recursive(n-1) + fib_recursive(n - 2)

def fib_recursive_tail(n):
    def fib_aux(a, b, n):
        return fib_aux(b, a+b, n-1) if n > 1 else a
    return fib_aux(1, 1, n)

def main ():
    print fib_iterative(5)
    print fib_recursive(5)
    print fib_recursive_tail(5)

if __name__ == '__main__':
    main()