_valid_func_char(char) {
        return (
            'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_.'.indexOf(
                char
            ) > -1
        );
    }
/**
     * Returns whether provided char is a valid function syntax char
     *
     * @param {String} char
     * @returns {Boolean} Boolean
     */
Returns whether provided char is a valid function syntax char
@param {String} char
@returns {Boolean} Boolean
Returns whether provided char is a valid function syntax char @param { String } char @returns { Boolean } Boolean
_valid_func_char(char) {
        return (
            'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_.'.indexOf(
                char
            ) > -1
        );
    }
_valid_func_char ( char ) { return ( 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_.' . indexOf ( char ) > - 1 ) ; }
Returns whether provided char is a valid function syntax char
 @param {String} char
 @returns {Boolean} Boolean
Returns whether provided char is a valid function syntax char @param { String } char @returns { Boolean } Boolean