text: module.exports = class DepthCalculator {
      calculateDepth(arr) {
          let n = 1;
          for(let i=0; i<arr.length; i++) {
              if(Array.isArray(arr[i])) {
                  let m = 1+this.calculateDepth(arr[i]);
                  n = n<m?m:n;
              } 
          }
          return n;
      }
  };