protected function evaluateFunction($function, array $argv_list)
 {
     $results = array();
     foreach ($argv_list as $argv) {
         $results[] = $this->getViewer()->getPHID();
     }
     return DifferentialResponsibleDatasource::expandResponsibleUsers($this->getViewer(), $results);
 }
 protected function evaluateValues(array $values)
 {
     return DifferentialResponsibleDatasource::expandResponsibleUsers($this->getViewer(), $values);
 }