Sharing part of a function

[Betty Hollinshead]

"Memoising" is the answer -- see "Python Algorithms" by Magnus Lie Hetland.
In the mean time, here a simplified version of "memoising" using a dict.
This version handles pretty large fibonacci numbers!

# fibonacci sequence
# memoised - but using a simple dictionary (see Python Algorithms, p177)

memo    = {}
memo[1] = 1
memo[2] = 2

def fib(n):
    if n in memo:
        return memo[n]
    else:
        memo[n] = fib(n - 1) + fib(n - 2)
        return memo[n]


print(100, fib(100))
print(memo)