public function implodeKeys(string $glue = ''): string
    {
        return $this->implode_recursive($glue, $this->getArray(), true);
    }
public function implodeKeys(string $glue = ''): string
    {
        return $this->implode_recursive($glue, $this->getArray(), true);
    }
public function implodeKeys ( string $ glue = '' ) : string { return $ this -> implode_recursive ( $ glue , $ this -> getArray ( ) , true ) ; }
Implodes the keys of this array.

@param string $glue

@return string
Implodes the keys of this array .