public void RegisterRemoveAssignment(PropGraphNodeDescriptor lhs, PropGraphNodeDescriptor rhs)
{
if (lhs != null && rhs != null)
{
var typesToDelete = PropagationGraph.TypesInEdge(rhs, lhs);
PropagationGraph.RemoveTypes(lhs, typesToDelete);
PropagationGraph.AddToDeletionWorkList(lhs);
}
}
