How to use the @ckeditor/ckeditor5-widget/src/utils.isWidget function in @ckeditor/ckeditor5-widget

export function isCustomWidget( widget, viewElement ) {
  // const symbol = symbols[widget]
  if (typeof viewElement !== 'undefined' && viewElement !== null) {
     // return !!viewElement.getCustomProperty( symbol ) && isWidget( viewElement );
     return !!viewElement.getCustomProperty( formSymbol ) && isWidget( viewElement );
  } else {
    return false
  }
}

it( 'should be widgetized', () => {
			expect( isWidget( element ) ).to.be.true;
		} );

export function isAcasiWidget( viewElement ) {
  let acasiTest = viewElement.getCustomProperty( acasiSymbol )
  return !!acasiTest && isWidget( viewElement );
}

export function isTableWidget( viewElement ) {
	return !!viewElement.getCustomProperty( 'table' ) && isWidget( viewElement );
}

export function isMediaWidget( viewElement ) {
	return !!viewElement.getCustomProperty( 'media' ) && isWidget( viewElement );
}

export function isImageWidget( viewElement ) {
	return !!viewElement.getCustomProperty( 'image' ) && isWidget( viewElement );
}