```Python
with open("file.txt") as file:
    file.read()
```

Nas versões mais recentes de Python, há também um **gerenciador de contexto assíncrono**. Você o usaria com `async with`:

```Python
async with lifespan(app):
    await do_stuff()
```

package kms

import (
	"bytes"
	"sort"
	"unicode/utf8"
)

// Context is a set of key-value pairs that
// are associated with a generate data encryption
// key (DEK).
//
// A KMS implementation may bind the context to the
// generated DEK such that the same context must be
// provided when decrypting an encrypted DEK.
type Context map[string]string

// MarshalText returns a canonical text representation of

import (
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/client-go/rest"

	"istio.io/istio/istioctl/pkg/util/handlers"
	"istio.io/istio/pkg/kube"
	"istio.io/istio/pkg/ptr"
)

type Context interface {
	// CLIClient returns a client for the default revision
	CLIClient() (kube.CLIClient, error)
	// CLIClientWithRevision returns a client for the given revision
	CLIClientWithRevision(rev string) (kube.CLIClient, error)

==============================================================================*/
#ifndef TENSORFLOW_C_EAGER_ABSTRACT_CONTEXT_H_
#define TENSORFLOW_C_EAGER_ABSTRACT_CONTEXT_H_

#include <memory>

#include "tensorflow/c/eager/abstract_function.h"
#include "tensorflow/c/eager/abstract_operation.h"

namespace tensorflow {

// Abstract interface to a context.
//
// This serves as a factory for creating `AbstractOperation`s and for

limitations under the License.
==============================================================================*/
#ifndef TENSORFLOW_C_EXPERIMENTAL_GRADIENTS_TAPE_TAPE_CONTEXT_H_
#define TENSORFLOW_C_EXPERIMENTAL_GRADIENTS_TAPE_TAPE_CONTEXT_H_

#include "tensorflow/c/eager/abstract_context.h"
#include "tensorflow/c/experimental/gradients/tape/tape_operation.h"

namespace tensorflow {
namespace gradients {

limitations under the License.
==============================================================================*/
#include "tensorflow/c/experimental/gradients/tape/tape_context.h"

#include "tensorflow/c/eager/abstract_context.h"
#include "tensorflow/c/experimental/gradients/tape/tape_operation.h"

namespace tensorflow {
namespace gradients {
TapeContext::TapeContext(AbstractContext* c, Tape* tape,

// the TFE_Context structure.
typedef struct TFE_Context TFE_Context;

namespace tensorflow {

DEFINE_CONVERSION_FUNCTIONS(tensorflow::ImmediateExecutionContext, TFE_Context);

}  // namespace tensorflow

{
    "properties": {
      "term": {
        "type": "keyword"
      },
      "content": {
        "type": "keyword"
      },
      "virtualHost": {
        "type": "keyword"
      },
      "sortOrder": {
        "type": "integer"
      },
      "createdBy": {
        "type": "keyword"
      },
      "createdTime": {
        "type": "long"
      },
      "updatedBy": {
        "type": "keyword"
      },

#ifndef TENSORFLOW_C_EAGER_IMMEDIATE_EXECUTION_CONTEXT_H_
#define TENSORFLOW_C_EAGER_IMMEDIATE_EXECUTION_CONTEXT_H_

#include <functional>
#include <map>
#include <memory>
#include <vector>

#include "absl/types/optional.h"
#include "absl/types/span.h"
#include "tensorflow/c/eager/abstract_context.h"
#include "tensorflow/c/eager/immediate_execution_distributed_manager.h"

}

// extractMetadataFromReq extracts metadata from HTTP header and HTTP queryString.
func extractMetadataFromReq(ctx context.Context, r *http.Request) (metadata map[string]string, err error) {
	return extractMetadata(ctx, textproto.MIMEHeader(r.Form), textproto.MIMEHeader(r.Header))
}

func extractMetadata(ctx context.Context, mimesHeader ...textproto.MIMEHeader) (metadata map[string]string, err error) {
	metadata = make(map[string]string)