A decorator that works as a simple cache

cache.py

from math import sqrt

def cache(F):
    """A simple cache decorator"""
    cache = dict()
    def wrapper(*args):
        try:
            return cache[args]
        except KeyError:
            # Result not in cache --> Calculate and store it
            result = F(*args)
            cache[args] = result
            return result
    
    return wrapper
    
@cache
def is_prime(x):
    """Non-accurate implementation of prime check"""
    iterations = 0
    for i in range(2, int(sqrt(x)) + 1):
        iterations += 1
        if i % x == 0:
            return False
    print('{} iterations'.format(iterations))
    return True