code: function base64ToBytes(str) {
      if (typeof atob === 'undefined' && typeof Buffer === 'function') {
          // node.js doesn't have atob
          var buffer = Buffer.from(str, 'base64');
          return new Uint8Array(buffer);
      }
      var byteStr = atob(str);
      var arr = new Uint8Array(byteStr.length);
      for (var i = 0; i < byteStr.length; i++) {
          arr[i] = byteStr.charCodeAt(i);
      }
      return arr;
  }
docs: Converts base64 string to array
  @param {string} str
  @return {Uint8Array}