How Migrate a Legacy Widget to dam?

I am making an attempt to tranform legacy widgets to dam, I used to be studying the docs, however I could not perceive the place to place this javascript code :

transforms: {
from: [
    {
        type: 'block',
        blocks: [ 'core/legacy-widget' ],
        isMatch: ( { idBase, occasion } ) => {
            if ( ! occasion?.uncooked ) {
                // Cannot remodel if uncooked occasion just isn't proven in REST API.
                return false;
            }
            return idBase === 'example_widget';
        },
        remodel: ( { occasion } ) => {
            return createBlock( 'instance/block', {
                identify: occasion.uncooked.identify,
            } );
        },
    },
]},

it says that I ought to add this javascript to my block’s definition. the place is that?

wordpress docs: https://developer.wordpress.org/block-editor/how-to-guides/widgets/legacy-widget-block/