How to get the button clicked in FormAPI

How do I get what the button name was clicked using FormAPI?
i create buttons with

PHP:

$form = $this->getFormAPI()->createSimpleForm( function ( Player $player, ?int $result = null ) {
                 
                    if ( $result === null ) {
                        return;
                    }
                 
                    switch ($result) {
                        case 0:
                            $player->sendMessage("hi");
                            break;
                    }
                 
                    return;
                } );
                $form->setTitle( $title );
                $form->setContent( $content );
                $form->addButton( "hello");
                $form->addButton( "hey");
                $form->sendToPlayer( $player );

how do i get what button the player clicked
like if(buttonclicked == "hello"){}

 

1. button that you'll add gets index 0
2. button that you'll add gets index 1
3 ... 2
...

in function that you will add to the form you use $result instead of index

so hello button has index 0

PHP:

if($result === 0) {

} 

 

I know but i want to know the name of the button they clicked