def get_exit_code(matches):
    """ Determine exit code """
    exit_code = 0
    for match in matches:
        if match.rule.id[0] == 'I':
            exit_code = exit_code | 8
        elif match.rule.id[0] == 'W':
            exit_code = exit_code | 4
        elif match.rule.id[0] == 'E':
            exit_code = exit_code | 2
    return exit_code
