How to make a recursive populace?

Question

MongoDB

There is a scheme comment, with a field repliesin which there are others comment, which can also have replies, and so on ad infinitum.

Post.findOne({slug}).populate({path: 'comments', populate: {path: 'replies', populate: {path: 'replies'}}}).exec()

Such a code populates only to the specified nesting level, but what if these levels are not 3 like here, but 5-10? How to do automatic recursive populace?