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 {

    🎲 👆 💪 ▶️ 🆕 ⏬, ⚖️ 👆 🤚 🎡 🏃 ⚫️. 🤷

### 🔆 🔢

🥇 👜 👀, 👈 👥 ⚖ 🔁 🔢 ⏮️ `yield`. 👉 📶 🎏 🔗 ⏮️ `yield`.

```Python hl_lines="14-19"
{!../../../docs_src/events/tutorial003.py!}
```

🥇 🍕 🔢, ⏭ `yield`, 🔜 🛠️ **⏭** 🈸 ▶️.

& 🍕 ⏮️ `yield` 🔜 🛠️ **⏮️** 🈸 ✔️ 🏁.

### 🔁 🔑 👨‍💼

🚥 👆 ✅, 🔢 🎀 ⏮️ `@asynccontextmanager`.

👈 🗜 🔢 🔘 🕳 🤙 "**🔁 🔑 👨‍💼**".

            runPropertyAccessResolution(
                propertyAccess,
                onLocalValue = { yield(AssignmentResolution.ReassignLocalVal(it.localValue)) },
                onProperty = { yield(AssignmentResolution.AssignProperty(PropertyReferenceResolution(it.receiver, it.property))) },
                onExternalObject = { yield(AssignmentResolution.ReassignExternal(it)) }
            )
        }

// CHECK:   call @while_cond_10_frozen0
// CHECK:   yield
// CHECK: ^bb0([[ARGS]]):
// CHECK:   call @while_body
// CHECK:   yield
// CHECK: while_body
// CHECK: while_cond

// INLINE: tfl.while
// INLINE: ^bb0([[ARGS:.*]]):
// INLINE:   tf.Less
// INLINE:   yield
// INLINE: ^bb0([[ARGS]]):
// INLINE:   %cst_2 = arith.constant
// INLINE:   yield
// INLINE-NOT: while_body
// INLINE-NOT: while_cond

    %2 = "tf.IfRegion"(%arg0) ({
      %3 = "tf.StringToNumber"(%arg1) {out_type = f32} : (tensor<!tf_type.string>) -> tensor<f32>
      "tf.Yield"(%3) : (tensor<f32>) -> ()
     },  {
      %4 = "tf.Const"() {value = dense<1.0> : tensor<f32>} : () -> tensor<f32>
      "tf.Yield"(%4) : (tensor<f32>) -> ()
    }) {is_stateless = true} : (tensor<i1>) -> (tensor<f32>)
    %5 = "tf.Identity"(%2) : (tensor<f32>) -> tensor<f32>

    "tfl.yield"(%1) : (tensor<i1>) -> ()
  },  {
  ^bb0(%arg0: tensor<*xi32>, %arg1: tensor<*xf32>):
    // CHECK: call @WhileOp_body
    // CHECK-SAME: (tensor<*xi32>, tensor<*xf32>, tensor<i32>)
    %1:3 = func.call @WhileOp_body(%arg0, %arg1, %cst) : (tensor<*xi32>, tensor<*xf32>, tensor<i32>) -> (tensor<*xi32>, tensor<*xf32>, tensor<i32>)
    "tfl.yield"(%1#0, %1#1) : (tensor<*xi32>, tensor<*xf32>) -> ()

  auto it = block.rbegin();
  YieldOp yield = dyn_cast<YieldOp>(*it++);

  if (it == block.rend()) return std::nullopt;

  // Operation which is expected to consume all the call results.
  Operation* call_consumer = yield;

  // Allow a single ToBoolOp between the call and the yield (valid only
  // when the yield has a single operand)
  if (allow_to_bool && yield.getNumOperands() == 1 && isa<ToBoolOp>(*it)) {

A primeira coisa a notar, é que estamos definindo uma função assíncrona com `yield`. Isso é muito semelhante à Dependências com `yield`.

```Python hl_lines="14-19"
{!../../../docs_src/events/tutorial003.py!}
```

A primeira parte da função, antes do `yield`, será  executada **antes** da aplicação inicializar.

E a parte posterior do `yield` irá executar **após** a aplicação ser encerrada.

### Gerenciador de Contexto Assíncrono