_arrayToString(semi_parsed) {
        let condition_string = {};

        for (let lvl = 1; lvl <= this._max_level; lvl++) {
            let relation = semi_parsed['l' + lvl].relation;
            let condition_counter = 1;

            condition_string['l' + lvl] = '';
            semi_parsed['l' + lvl].cond_str.forEach(cond => {
                condition_string['l' + lvl] += cond;
                if (condition_counter < semi_parsed['l' + lvl].cond_str.length || semi_parsed.hasOwnProperty('l' + (lvl + 1)))
                    condition_string['l' + lvl] += ' ' + relation + ' ';

                condition_counter++;
            });
        }

        return condition_string;
    }
/**
     * connect query strings with its own relation
     * @param {array} semi_parsed 
     */
connect query strings with its own relation
@param {array} semi_parsed
connect query strings with its own relation @param { array } semi_parsed
_arrayToString(semi_parsed) {
        let condition_string = {};
        for (let lvl = 1; lvl <= this._max_level; lvl++) {
            let relation = semi_parsed['l' + lvl].relation;
            let condition_counter = 1;
            condition_string['l' + lvl] = '';
            semi_parsed['l' + lvl].cond_str.forEach(cond => {
                condition_string['l' + lvl] += cond;
                if (condition_counter < semi_parsed['l' + lvl].cond_str.length || semi_parsed.hasOwnProperty('l' + (lvl + 1)))
                    condition_string['l' + lvl] += ' ' + relation + ' ';
                condition_counter++;
            });
        }
        return condition_string;
    }
_arrayToString ( semi_parsed ) { let condition_string = { } ; for ( let lvl = 1 ; lvl <= this . _max_level ; lvl ++ ) { let relation = semi_parsed [ 'l' + lvl ] . relation ; let condition_counter = 1 ; condition_string [ 'l' + lvl ] = '' ; semi_parsed [ 'l' + lvl ] . cond_str . forEach ( cond => { condition_string [ 'l' + lvl ] += cond ; if ( condition_counter < semi_parsed [ 'l' + lvl ] . cond_str . length || semi_parsed . hasOwnProperty ( 'l' + ( lvl + 1 ) ) ) condition_string [ 'l' + lvl ] += ' ' + relation + ' ' ; condition_counter ++ ; } ) ; } return condition_string ; }
connect query strings with its own relation
 @param {array} semi_parsed
connect query strings with its own relation @param { array } semi_parsed