code: public function getGroupsChunk($options = array(), $reverse = false)
      {
          $data = $this->__preparedRequest('group_list', 'GET', $options);
          $groups_raw = (array)$data->results;
          $resultArr = array();
          foreach ($groups_raw as $group_raw) {
              $resultArr[] = new Group($group_raw->id, $this);
          }
          return $this->__preparePagedParams($data, $reverse, $resultArr);
      }
docs: Get portion of groups from server respecting filters
  
  @param array $options
  @param bool $reverse
  @return array
  @throws \Exception