public function nextY()
    {
        if ($this->nextYExists()) {
            $this->seekY($this->keyY()+1);
        } else {
            $this->y = null;
        }
        return $this;
    }
public function nextY()
    {
        if ($this->nextYExists()) {
            $this->seekY($this->keyY()+1);
        } else {
            $this->y = null;
        }
        return $this;
    }
public function nextY ( ) { if ( $ this -> nextYExists ( ) ) { $ this -> seekY ( $ this -> keyY ( ) + 1 ) ; } else { $ this -> y = null ; } return $ this ; }
Seek to current `y` plus 1

@return  $this
Seek to current y plus 1