Usage of lru_cache

clockdemo.py

import time
import functools

def clock(func):
    @functools.wraps(func)   # relace with orig func's __name__ and __doc__
    def clocked(*args, **kwargs):
        t0 = time.time()
        result = func(*args, **kwargs)
        elapsed = time.time() - t0
        name = func.__name__
        arg_lst = []
        if args:
            arg_lst.append(', '.join(repr(arg) for arg in args))
        if kwargs:
            pairs = ['%s=%r' % (k, w) for k, w in sorted(kwargs.items())]
            arg_lst = ', '.join(pairs)

        arg_str = ', '.join(arg_lst)
        print('[%0.8fs] %s(%s) -> %r' % (elapsed, name, arg_str, result))
        return result

    return clocked


@clock
def factorial(n):
    return 1 if n < 2 else n * factorial(n - 1)


@functools.lru_cache()  # if without, performance goes down
@clock
def fibonacci(n):
    if n < 2:
        return n
    return fibonacci(n - 2) + fibonacci(n - 1)


if __name__ == '__main__':
    print(fibonacci(6))