f.py

from functools import wraps

def c(f):
    @wraps(f)
    def w(k):
        if k in d:
            return d[k]
        else:
            d[k] = f(k)
            return d[k]
    return w

@c
def f(k):
    """recursive fibonacci"""
    if k == 1 or k == 2:
        return 1
    elif k > 2 :
        return f(k-1) + f(k-2)
    else:
        raise ValueError("k > 0")
        
def f(k):
    """non-recursive fibonacci"""
    a1 = 1
    a2 = 1
    
    if k == 1 or k == 2:
        return a1
    elif k > 2:
        for i in range(3, k+1):
            s = a2 + a1
            a2 = a1
            a1 = s
        return a1
    else:
        raise ValueError("k > 0")
        
def cf(int k):
    """cythonised non-recursive fibonacci"""
    cdef int a1 = 1
    cdef int a2 = 1
    cdef int i, s
    
    if k == 1 or k == 2:
        return a1
    elif k > 2:
        for i in range(3, k+1):
            s = a2 + a1
            a2 = a1
            a1 = s
        return a1
    else:
        raise ValueError("k > 0")