code: protected function addReason($id, $reason)
      {
          if (!isset($this->reasonSeen[$id])) {
              $this->reasonSeen[$id] = true;
              $this->reasons[$this->section][] = $reason;
          }
      }
docs: Store a reason descriptor but ignore duplicates
  
  @param string $id     A canonical identifier for the reason
  @param string $reason The reason descriptor