code: function(after, before, inc, iterator) {
          var args = {
                  before: before,
                  after: after,
                  inc: inc
              }
  
          if (iterator) {
              return this._iter(
                  new CallbackIterResult('between', args, iterator));
          } else {
              var result = this._cacheGet('between', args);
              if (result === false) {
                  result = this._iter(new IterResult('between', args));
                  this._cacheAdd('between', result, args);
              }
              return result;
          }
      }
docs: Returns all the occurrences of the rrule between after and before.
  The inc keyword defines what happens if after and/or before are
  themselves occurrences. With inc == True, they will be included in the
  list, if they are found in the recurrence set.
  @return Array