You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: metadata.go
    path of file: ./repos/corteza/server/vendor/cloud.google.com/go/compute/metadata
    
    the code of the file until where you have to start completion: // Copyright 2014 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package metadata provides access to Google Compute Engine (GCE)
// metadata and API service accounts.
//
// This package is a wrapper around the GCE metadata service,
// as documented at https://cloud.google.com/compute/docs/metadata/overview.
package metadata // import "cloud.google.com/go/compute/metadata"

import (
	"context
    
func (c *Client) getETag(suffix string) (value, etag string, err error) {
	ctx := context.TODO()
	// Using a fixed IP makes it very difficult to spoof the metadata service in
	// a container, which is an important use-case for local testing of cloud
	// deployments. To enable spoofing of the metadata service, the environment
	// variable GCE_METADATA_HOST is first inspected to decide where metadata
	// requests shall go.
	host := os.Getenv(metadataHostEnv)
	if host == "" {
		// Using 169.254.169.254 instead of "metadata" here because Go
		// binaries built with the "netgo" tag and without cgo won't
		// know the search suffix for "metadata" is
		// ".google.internal", and this IP address is documented as
		// being stable anyway.
		host = metadataIP
	}
	suffix = strings.TrimLeft(suffix, "/")
	u := "http://" + host + "/computeMetadata/v1/" + suffix
	req, err := http.NewRequest("GET", u, nil)
	if err != nil {
		return "", "", err
	}
	req.Header.Set("Metadata-Flavor", "Google")
	req.Header.Set("User-Agent", userAgent)
	var res *http.Response
	var reqErr error
	retryer := newRetryer()
	for {
		res, reqErr = c.hc.Do(req)
		var code int
		if res != nil {
			code = res.StatusCode
		}
		if delay, shouldRetry := retryer.Retry(code, reqErr); shouldRetry {
			if err := sleep(ctx, delay); err != nil {
				return "", "", err
			}
			continue
		}
		break
	}
	if reqErr != nil {
		return "", "", reqErr
	}
	defer res.Body.Close()
	if res.StatusCode == http.StatusNotFound {
		return "", "", NotDefinedError(suffix)
	}
	all, err := ioutil.ReadAll(res.Body)
	if err != nil {
		return "", "", err
	}
	if res.StatusCode != 200 {
		return "", "", &Error{Code: res.StatusCode, Message: string(all)}
	}
	return string(all), res.Header.Get("Etag"), nil
}