I love regular expressions as much as anybody, but I never understood why people wrote code like that.

r"\s" is repeated 6 times in there, each time with a comment. Is there a reason nobody uses DRY when writing a regexp?

    spaces = r"\s*"
    number = r"([-+]?\d+)"
    bracket = r"([\[\]])"
    finder = re.compile(spaces.join(["^", bracket, number, ",", number, bracket, "$"]))