functools is a standard library in Python, offering utility for functional programming.

Use lru_cache to memoize function calls:

from functools import lru_cache

@lru_cache(maxsize=None)
def fib(n):
    if n < 2:
        return n
    return fib(n-1) + fib(n-2)

Resources

For docs, see: https://docs.python.org/3/library/functools.html