code: function setValueByPath(o, path, val) {
          var len = path.length - 1, s = o;
          if (len >= 0) {
              for (var i = 0; i < len; i++) {
                  o = o[path[i]];
              }
              if (o !== undefined) {
                  o[path[i]] = val;
              } else {
                  s = undefined;
              }
          }
          return s;
      }
docs: /*
  o, [x,y,z], val => o[x][y][z]=val
   /*
  o, [x,y,z], val => o[x][y][z]=val