vector.js
function drillRec(v){
        const next = v.get(0);
        if(v.length > 1 || !isAVector(next)) return v;
        return drillRec(next);
    }
function drillRec(v){
        const next = v.get(0);
        if(v.length > 1 || !isAVector(next)) return v;
        return drillRec(next);
    }
function drillRec ( v ) { const next = v . get ( 0 ) ; if ( v . length > 1 || ! isAVector ( next ) ) return v ; return drillRec ( next ) ; }
drill to first level with >1 value
drill to first level with > 1 value