How to use the @material/menu.Corner.TOP_LEFT function in @material/menu

return function (event) {
        let offset = parseInt(element.dataset.rightOffset);
        let placement = element.dataset.placement === 'contextual' ? Corner.TOP_LEFT : Corner.BOTTOM_LEFT;
        menu.setAbsolutePosition(event.clientX, event.clientY);
        menu.setAnchorMargin({left: offset});
        menu.setAnchorCorner(placement);
        menu.open = !menu.open;
        event.stopPropagation();
    };
}