                var accept = 'a' <= tok && tok <= 'z' || 'A' <= tok && tok <= 'Z' || '0' <= tok && tok <= '9' || ['!', '#', '$', '%', '&', '\'', '*', '+', '-', '/', '=', '?', '^', '_', '`', '{', '|', '}', '~'].indexOf(tok) >= 0;