def is_submodule(line):
    """Return True if the line is a valid submodule statement."""
    if len(line) < 2:
        # XXX: This is just to prevent index error in the next test
        #   Not entirely sure what this ought to be, come back to it...
        return False

    if (line[0], line[1]) != ('submodule', '('):
        return False

    # Not a great test, but enough to get things going.
    if len(line) == 5 and line[3] != ')':
        return False

    if len(line) == 7 and (line[4], line[6]) != (':', ')'):
        return False

    return True