code: protected function build()/*# : string */
      {
          $result = [];
  
          foreach ($this->getConfig() as $part) {
              $built = call_user_func([$this, $part['func']]);
              if (!empty($built)) {
                  $result[] =
                      $part['prefix'] . (empty($part['prefix']) ? '' : ' ') .
                      join($part['join'], $built);
              }
          }
          return '(' . join($this->settings['seperator'], $result) . ')';
      }
docs: {@inheritDoc}