def get_code(filename='arcade.intcodemachine'):
    """ Get the machine code for the arcade, a list of numbers. """
    # The arcade.intcode file is my puzzle input from Day 13, Advent of Code 2019.
    # Each registered user gets a slightly different version of the code.
    try:
        with open(filename) as codefile:
            raw = codefile.read().strip()
            code = [int(digits.strip()) for digits in raw.split(',')]
            return code
    except:
        raise Exception(f"Couldn't load intcodemachine from '{filename}'.")