fibonacci with memoization in python

fib.py

# Usage: python fib.py <number>

import sys

cache = {}

def main():
	verbose = '-v' in sys.argv
	n = int(sys.argv[1])
	for i in range(n): 
		fni = fib(i)
		if verbose:
			print(f"fib({i}) = {fni}")
	print(f"fib({n}) = {fib(n)}");

def fib(n):
	if n == 0 or n == 1:
		return 1
	if n in cache.keys():
		return cache.get(n)
	fn1 = fib(n-1)
	fn2 = fib(n-2)
	cache[n-1] = fn1
	cache[n-2] = fn2
	cache[n] = fn1 + fn2
	return cache[n]

if __name__ == '__main__':
	main()