I'm going through Immutable.js's source code and there's an ownerID field that I don't understand.
Here's the source for Map.asMutable() and Map.asImmutable(): https://github.com/facebook/immutable-js/blob/master/src/Map.js#L171
It seems like the only difference between a mutable and an immutable object are their ownerIDs. What is an ownerID and what is it used for?