function delete($obj,$f=null) { $data = $this->reject(function($x) { return equ($x, $obj); }); if($data->size() == $this->size()) return is_callable($f) ? $f() : $f; $this->DATA = $data->native(); return $obj; }
function member($obj) { return $this->find(function($y) use($obj) { return equ($obj, $y); }) != null; }