forDocument example in TypeScript

forDocument.ts

function forDocument(ownerDocument: Document) {
	return lang.partial(this, ownerDocument);
}

var byId:{
	(ownerDocument: Document, id: string);
	forDocument: (ownerDocument: Document) => (id: string) => Node;
} = <any> function (ownerDocument, id) {
	return ownerDocument.getElementById(id);
}
byId.forDocument = forDocument.bind(byId);

var dom = {
	byId: byId.forDocument(document)
};