- Each iteration of the graph is one single iteration in Pregel (ie. no more "{node}:edges" nodes)
- .update_state() now acts exactly as one of the nodes in the graph (which can be chosen), which makes human-in-the-loop scenarios where you want to override the actions of a specific node a lot easier to build
- Graph/StateGraph.compile() now delegate adding nodes/edges/etc to dedicated methods that operate on the Pregel object, which is 90% of the way towards dynamic graphs where nodes and edges can be added during execution
