public static bool BackwardsMoveNext(ref TraversalEnumerationState state) => -- state.Index >= 0;
public readonly bool MoveNext <TCollection>( TCollection blocks, ref TraversalEnumerationState state) where TCollection : IReadOnlyList <BasicBlock> => TraversalOrder.BackwardsMoveNext(ref state);
public static bool ForwardsMoveNext <TCollection>( TCollection blocks, ref TraversalEnumerationState state) where TCollection : IReadOnlyList <BasicBlock> => ++ state.Index < blocks.Count;