walk

type Cursor[N any] struct {
	Node        N
	Branches    []N
	BranchIndex int
}

type Order int

type SimpleVisitorFunc[N any] func(node N, visitorHandler VisitorHandler)

type Visitor[N any] interface {
	VisitorHandler

	Enter(node N)
	Visit(node N)
	Exit(node N)
}

type VisitorHandler interface {
	Consume()
	WasConsumed() bool
	Done() bool
	Error() error
	SetDone()
	SetError(err error)
	SetErrorf(format string, args ...any)
}