refactoring Node: seperate class for the collection of Nodes?

[Lyla-Fischer]

I just notice that the Node class is very large, and it has a lot of classmethods. I feel like a lot of the classmethods relate to dealing with the collection of nodes in a class variable, which feels like it should be in a seperate class to me (a collection of Nodes is not a Node), even if that class is a singleton.

[ahopkins]

Makes sense.