Collatz Conjecture Memoisation

memo.py

def memo(f):
    def func(*args):
        if args not in func.cache: 
            func.cache[args] = f(*args)
        return func.cache[args]
    func.cache = {}
    return func

@memo
def collatz(n):
    if n == 1:
        count, seq = 0, []
    elif n % 2:
        count, seq = collatz(3 * n + 1)
    else:
        count, seq = collatz(n // 2)
    return count + 1, [n] + seq