public function nextkey() {
		if ( $this->keys === null ) {
			return $this->firstkey();
		}

		return empty( $this->keys ) ? false : array_shift( $this->keys );
	}
public function nextkey() {
		if ( $this->keys === null ) {
			return $this->firstkey();
		}

		return empty( $this->keys ) ? false : array_shift( $this->keys );
	}
public function nextkey ( ) { if ( $ this -> keys === null ) { return $ this -> firstkey ( ) ; } return empty ( $ this -> keys ) ? false : array_shift ( $ this -> keys ) ; }
Fetch next key

@return string
Fetch next key