⚫️ 5️⃣📆 😋 🤚 `HTTPException` ⚖️ 🎏 🚪 📟, ⏮️ `yield`. ✋️ **⚫️ 🏆 🚫 👷**.

🚪 📟 🔗 ⏮️ `yield` 🛠️ *⏮️* 📨 📨, [⚠ 🐕‍🦺](../handling-errors.md#_4){.internal-link target=_blank} 🔜 ✔️ ⏪ 🏃. 📤 🕳 😽 ⚠ 🚮 👆 🔗 🚪 📟 (⏮️ `yield`).

, 🚥 👆 🤚 `HTTPException` ⏮️ `yield`, 🔢 (⚖️ 🙆 🛃) ⚠ 🐕‍🦺 👈 ✊ `HTTPException`Ⓜ & 📨 🇺🇸🔍 4️⃣0️⃣0️⃣ 📨 🏆 🚫 📤 ✊ 👈 ⚠ 🚫🔜.

👉 ⚫️❔ ✔ 🕳 ⚒ 🔗 (✅ 💽 🎉), 🖼, ⚙️ 🖥 📋.

package main

var gj int

func yield4x(yield func() bool) {
	_ = yield() && yield() && yield() && yield()
}

func yield4(yield func(int) bool) {
	_ = yield(1) && yield(2) && yield(3) && yield(4)
}

func yield3(yield func(int) bool) {
	_ = yield(1) && yield(2) && yield(3)
}

func yield2(yield func(int) bool) {
	_ = yield(1) && yield(2)
}

func testfunc0() {
	j := 0
	for range yield4x {

			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 {

// 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 {

	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-- {

	// in the middle of walking a node. Previously, incorrect handling of the
	// boolean returned by the yield function resulted in the iterator calling
	// yield for sibling nodes even after yield had returned false. With that
	// bug, this test failed with a runtime panic.
	src := "package p\ntype T struct {\n\tF int `json:\"f\"` // a field\n}\n"

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "", src, 0)
	if err != nil {