Pymongo has deprecated the save logic, even though
	MongoDB still advertizes that logic in the core API:
	https://docs.mongodb.com/manual/reference/method/db.collection.save/

	This function provides a compatible interface.

def save(coll, to_save):
	"""
	Pymongo has deprecated the save logic, even though
	MongoDB still advertizes that logic in the core API:
	https://docs.mongodb.com/manual/reference/method/db.collection.save/

	This function provides a compatible interface.
	"""
	filter = Projection(['_id'], to_save)
	upsert_replace = functools.partial(coll.replace_one, filter, upsert=True)
	op = upsert_replace if filter else coll.insert_one
	return op(to_save)