def _different(left, right, f):
    """
    true if entry f is different between left and right ZipFile
    instances
    """

    l = left.getinfo(f)
    r = right.getinfo(f)

    if (l.file_size == r.file_size) and (l.CRC == r.CRC):
        # ok, they seem passibly similar, let's deep check them.
        return _deep_different(left, right, f)

    else:
        # yup, they're different
        return True
true if entry f is different between left and right ZipFile
    instances