code: function indexOf(element, fromIndex) {
      /* jshint validthis:true */
      var arr = toArray(this),
          index;
  
      if (fromIndex) {
          arr = arr.slice(fromIndex);
      }
  
      index = binarySearch(arr, element, this.comparator);
  
      if (index < 0) {
          return -1;
      } else {
          return index;
      }
  }
docs: Works like Array.prototype.indexOf but uses a faster binary search.
  
  Same signature as Array.prototype.indexOf
  @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf