depthFirst() order:
   A
   B
   C
   C
   E
   E
   B
   C
   C
   A
breadthFirst() order:
   A
   B
   C
   C
   E
preOrder() order:
   A
   B
   C
   E
   C
preOrderDistinct() order:
   A
   B
   C
   D
   F
   E
postOrder() order:
   C
   E
   B
   C
   A
preOrderDistinct() order:
   F
   D
   C
   E
   B
   A
depthFirstDistinct() order:
   A
   B
   C
   D
   F
   F
   D
   C
   E
   E
   B
   A
depthFirstSteps() order:
   DfsStep[A, 0, true]
   DfsStep[B, 1, true]
   DfsStep[C, 2, true]
   DfsStep[C, 2, false]
   DfsStep[E, 2, true]
   DfsStep[E, 2, false]
   DfsStep[B, 1, false]
   DfsStep[C, 1, true]
   DfsStep[C, 1, false]
   DfsStep[A, 0, false]
depthFirstSteps() (with prune) order:
   DfsStep[A, 0, true]
   DfsStep[B, 1, true]
   --pruned
   DfsStep[C, 1, true]
   DfsStep[C, 1, false]
   DfsStep[A, 0, false]
depthFirstDistinctSteps() order:
   DfsStep[A, 0, true]
   DfsStep[B, 1, true]
   DfsStep[C, 2, true]
   DfsStep[D, 3, true]
   DfsStep[F, 4, true]
   DfsStep[F, 4, false]
   DfsStep[D, 3, false]
   DfsStep[C, 2, false]
   DfsStep[E, 2, true]
   DfsStep[E, 2, false]
   DfsStep[B, 1, false]
   DfsStep[A, 0, false]
depthFirstDistinct() (with marker func) order:
   A
   Ba
   C
   D
   F
   F
   D
   C
   E
   E
   Ba
   A
Depth-first order with cycle:
   A
   B
   A
   B
   A
   B
   A
   B
   A
   B
   ...
breadthFirst() order distinct:
   A
   B
   C
   D
   E
   F
breadhtFirstSteps() order:
   TraversalStep[A, 0]
   TraversalStep[B, 1]
   TraversalStep[C, 1]
   TraversalStep[C, 2]
   TraversalStep[E, 2]
breadhtFirstDistinctSteps() order:
   TraversalStep[A, 0]
   TraversalStep[B, 1]
   TraversalStep[C, 1]
   TraversalStep[D, 1]
   TraversalStep[E, 2]
   TraversalStep[F, 2]
breadthFirstSteps() (with prune) order:
   TraversalStep[A, 0]
   TraversalStep[B, 1]
   --pruned
   TraversalStep[C, 1]
Breadth-first order with cycle:
   A
   B
   C
   D
   A
   C
   E
   B
   D
   A
   B
   F
   B
   C
   D
   B
   D
   A
   C
   E
   ...
priority() alphabetic priority order:
   A
   C
   D
   C
   E
priority() alphabetic priority order:
   A
   C
   D
   E
prioritySteps() alphabetic priority order:
   TraversalStep[A, 0]
   TraversalStep[C, 1]
   TraversalStep[D, 1]
   TraversalStep[C, 2]
   TraversalStep[E, 2]
prioritySteps() (with prune) order:
   TraversalStep[A, 0]
   TraversalStep[B, 1]
   --pruned
   TraversalStep[D, 1]
   TraversalStep[C, 2]
   TraversalStep[E, 2]