* Runs a [TaskRunner] in a controlled environment so that everything is sequential and
 * deterministic.
 *
 * This class ensures that at most one thread is running at a time. This is initially the JUnit test
 * thread, which yields its execution privilege while calling [runTasks], [runNextTask], or
 * [advanceUntil]. These functions don't return until the task threads are all idle.
 *
 * Task threads release their execution privilege in these ways:
 *

			break
		}
		return func(yield func(Value) bool) {
			v = v.Elem()
			for i := range v.Len() {
				if !yield(ValueOf(i)) {
					return
				}
			}
		}
	case Array, Slice:
		return func(yield func(Value) bool) {
			for i := range v.Len() {
				if !yield(ValueOf(i)) {
					return
				}
			}
		}
	case String:
		return func(yield func(Value) bool) {
			for i := range v.String() {

	"testing"
)

type Seq2[T1, T2 any] func(yield func(T1, T2) bool)

// ofSliceIndex returns a Seq over the elements of s. It is equivalent
// to range s, except that it splits s into two halves and iterates
// in two separate goroutines.  This is racy if yield is racy, and yield
// will be racy if it contains an early exit.
func ofSliceIndex[T any, S ~[]T](s S) Seq2[int, T] {
	return func(yield func(int, T) bool) {
		c := make(chan bool, 2)

	return nil
}

func iterSimple(yield func(int) bool) {
	for range 3 {
		if !yield(5) {
			return
		}
	}
}

func iterNested(yield func(int) bool) {
	next, stop := iter.Pull(iterSimple)
	for {
		v, ok := next()
		if ok {
			if !yield(v) {
				stop()
			}
		} else {
			return
		}
	}
}

func iterLock(yield func(int) bool) {
	for range 3 {

import (
	"fmt"
	. "iter"
	"runtime"
	"testing"
)

func count(n int) Seq[int] {
	return func(yield func(int) bool) {
		for i := range n {
			if !yield(i) {
				break
			}
		}
	}
}

func squares(n int) Seq2[int, int64] {
	return func(yield func(int, int64) bool) {
		for i := range n {
			if !yield(i, int64(i)*int64(i)) {
				break
			}
		}
	}
}

func TestPull(t *testing.T) {

// When called as seq(yield), seq calls yield(v) for each value v in the sequence,
// stopping early if yield returns false.
type Seq[V any] func(yield func(V) bool)

// Seq2 is an iterator over sequences of pairs of values, most commonly key-value pairs.
// When called as seq(yield), seq calls yield(k, v) for each pair (k, v) in the sequence,
// stopping early if yield returns false.

	})
	return err
}

func iterSimple(yield func(int) bool) {
	for range 3 {
		if !yield(5) {
			return
		}
	}
}

func iterNested(yield func(int) bool) {
	next, stop := iter.Pull(iterSimple)
	for {
		v, ok := next()
		if ok {
			if !yield(v) {
				stop()
			}
		} else {
			return
		}
	}
}

func iterCallback(yield func(int) bool) {
	for range 3 {

  if (!control_node.GetBody().args_empty())
    return control_node.emitOpError() << "expects body without any arguments";

  Operation& yield = control_node.GetBody().back();
  if (!isa<YieldOp>(yield))
    return yield.emitOpError()
           << "invalid TFL.control_node terminator, yield expected";

  // Ensure that the terminator's operands and the control_node results match in
  // types.
  const int result_count =

	return func(yield func(K, V) bool) {
		for k, v := range m {
			if !yield(k, v) {
				return
			}
		}
	}
}

// Keys returns an iterator over keys in m.
// The iteration order is not specified and is not guaranteed
// to be the same from one call to the next.
func Keys[Map ~map[K]V, K comparable, V any](m Map) iter.Seq[K] {
	return func(yield func(K) bool) {
		for k := range m {

	return func(yield func(int, E) bool) {
		for i, v := range s {
			if !yield(i, v) {
				return
			}
		}
	}
}

// Backward returns an iterator over index-value pairs in the slice,
// traversing it backward. The indexes range from len(s)-1 down to 0.
func Backward[Slice ~[]E, E any](s Slice) iter.Seq2[int, E] {
	return func(yield func(int, E) bool) {
		for i := len(s) - 1; i >= 0; i-- {