text: module.exports = class DepthCalculator {
      calculateDepth(arr) {
          if (!(arr instanceof Array)) {
              return 0;
          }
          let countDepth = 0;
          for (let item of arr) {
              let depth = this.calculateDepth(item);
              if (countDepth < depth) {
                  countDepth = depth;
              }
          }
          return countDepth + 1;
      }
  };