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-- {

    // CHECK-SAME:       _xla_compile_device_type = "TPU"
    // CHECK-SAME:       device = "/job:localhost/replica:0/task:0/device:TPU:1"
    // CHECK:            "tf.Yield"(%[[FUNC_CALL]])
    // CHECK:            "tf.Yield"(%[[ARG_5]])
    // CHECK:          "tf.Yield"(%[[HAS_VALUE]], %[[IF]])
    %1 = "tf.ReduceDataset"(%arg0, %arg1) {
      Targuments = [],
      Tstate = [i64], device = "/job:localhost/replica:0/task:0/device:TPU:1",

from typing_extensions import Annotated


async def dependency_a():
    dep_a = generate_dep_a()
    try:
        yield dep_a
    finally:
        dep_a.close()


async def dependency_b(dep_a: Annotated[DepA, Depends(dependency_a)]):
    dep_b = generate_dep_b()
    try:
        yield dep_b
    finally:
        dep_b.close(dep_a)


async def dependency_c(dep_b: Annotated[DepB, Depends(dependency_b)]):

  ^bb0(%arg2: tensor<i32>, %arg3: tensor<i32>):
    %1 = "tf.OpA"() {is_stateless = true} : () -> tensor<i1>
    "tf.Yield"(%1) : (tensor<i1>) -> ()
  }, {
  ^bb0(%arg2: tensor<i32>, %arg3: tensor<i32>):
    %1 = "tf.GlobalIterId"() : () -> tensor<i64>
    "tf.Yield"(%arg2, %arg3) : (tensor<i32>, tensor<i32>) -> ()

      // CHECK-SAME: device = "/device:test_device:0"
      %3 = "tf_device.launch_func"(%2) {device = "/device:test_device:0", func = @_func} : (tensor<?xf32>) -> tensor<?xf32>

      // CHECK: tf_executor.yield %[[CALL_OUTPUT]]
      tf_executor.yield %3 : tensor<?xf32>
    }
    tf_executor.fetch %1#0 : tensor<?xf32>
  }
  func.return %0 : tensor<?xf32>
}

func.func @_func(%arg0: tensor<?xf32>) -> tensor<?xf32> {

    // CHECK: tf_executor.island wraps "tf.IdentityN"
    %0:3 = tf_executor.island {
      %1:2 = "tf.IdentityN"(%arg0, %arg1) : (tensor<i32>, tensor<f32>) -> (tensor<i32>, tensor<f32>) loc("identity@some_function")
      tf_executor.yield %1#0, %1#1 : tensor<i32>, tensor<f32> loc("identity@some_function")
    } loc("identity@some_function")
    tf_executor.fetch
  }
  func.return
}

// CHECK-LABEL: func @island_no_wrap_print_mismatched_results

// tf_executor.island, tf.Identity, and tf_executor.yield).

// CHECK-LABEL: "func.func"
// CHECK: sym_name = "island_one_op_all_locs_same"
// CHECK:    "tf_executor.graph"() ({
// CHECK-NEXT:      "tf_executor.island"() ({
// CHECK-NEXT:        "tf.Identity"(%{{.*}}) : (tensor<f32>) -> tensor<f32> loc("identity@some_function")
// CHECK-NEXT:        "tf_executor.yield"(%{{.*}}) : (tensor<f32>) -> () loc("identity@some_function")

client = TestClient(app)


def test_dependency_contextvars():
    """
    Check that custom middlewares don't affect the contextvar context for dependencies.

    The code before yield and the code after yield should be run in the same contextvar
    context, so that request_state_context_var.reset(contextvar_token).

    If they are run in a different context, that raises an error.
    """

        %5 = "tf.D"(%4) {device = "gpu0"} : (tensor<?xi32>) -> tensor<?xi32>
        // CHECK: tf_device.return %[[D_OUTPUT]]

        // CHECK: tf_executor.yield %[[GPU0_OUTPUT]]
        tf_executor.yield %5 : tensor<?xi32>
      }
      tf_executor.fetch %1#0 : tensor<?xi32>
    }
    func.return %0 : tensor<?xi32>
  }
}

// -----

        tf_device.return
      }
      tf_executor.yield
    }
    %1 = tf_executor.island {
      tf_device.replicate {n = 2 : i32, devices = {CORE_0 = ["/CPU:0", "/GPU:1"]}} {
        "tf_device.launch"() ({
          "tf.opA"() : () -> ()
          tf_device.return
        }) {device = "/TPU:1"} : () -> ()
        tf_device.return
      }
      tf_executor.yield
    }
    tf_executor.fetch
  }
  func.return