public static String tokenTypeName(int token_type)
    {
        String name = null;
        switch (token_type)
        {
            case PIPE:
                name = "PIPE";
                break;
            case REDIRECT_IN:
                name = "REDIRECT_IN";
                break;
            case REDIRECT_OUT:
                name = "REDIRECT_OUT";
                break;
            case APPEND:
                name = "APPEND";
                break;
            case SEPARATOR:
                name = "SEPARATOR";
                break;
            case AMPERSAND:
                name = "AMPERSAND";
                break;
            case VARIABLE:
                name = "VARIABLE";
                break;
            case QUOTED_STRING:
                name = "QUOTED_STRING";
                break;
            case STRING:
                name = "STRING";
                break;
            default: 
                Assertion.check(false); 
                break;
        }
        return name;
    }