React-dnd library. How to use DragLayer?

Question

React

React-dnd library.
https://react-dnd.github.io/react-dnd/
https://react-dnd.github.io/react-dnd/docs-overvie...
Those who used it, tell me how to use DragLayer. Where to render it? Under what conditions?
As I understand it, it is in case the html-5 snapshot of the element does not suit you. DragLayer overlays it. But about the use there is nothing.
How to use it?