docs: function(method, args, iterator) {
      var allowedMethods = ['all', 'between'];
      if (!_.include(allowedMethods, method)) {
          throw 'Invalid method "' + method
              + '". Only all and between works with iterator.'
      }
      this.add = function(date) {
          if (iterator(date, this._result.length)) {
              this._result.push(date);
              return true;
          }
          return false;
  
      };
  
      this.init(method, args);
  
  }