protected function joinOnEqualityQuery()
{
return <<<'ENG'
Join with: [array or iterator] filtered according to: { return $__o; } with parameters: [$__this] equaling { return $__i; } with parameters: [$__this] and correlate the values according to: { return [$__o, $__i]; } with parameters: [$__this]
Get the elements as itself
ENG;
}