original_string: private static function optional($feature) {
          if ($feature->getParent())
              return Logic::implies(Logic::is($feature), Logic::is($feature->getParent()));
      }
code: private static function optional($feature) {
          if ($feature->getParent())
              return Logic::implies(Logic::is($feature), Logic::is($feature->getParent()));
      }
code_tokens: private static function optional ( $ feature ) { if ( $ feature -> getParent ( ) ) return Logic :: implies ( Logic :: is ( $ feature ) , Logic :: is ( $ feature -> getParent ( ) ) ) ; }
docstring: Semantics for an optional feature.
  If an optional feature is selected, its parent is selected.
  @param Feature $feature
  @return callable
docstring_tokens: Semantics for an optional feature . If an optional feature is selected its parent is selected .