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: stackdriver.go
    path of file: ./repos/go-cloud/server/requestlog
    
    the code of the file until where you have to start completion: // Copyright 2018 The Go Cloud Development Kit Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file exc
    
func appendLatency(b []byte, d time.Duration) []byte {
	// Parses format understood by google-fluentd (which is looser than the documented LogEntry format).
	// See the comment at https://github.com/GoogleCloudPlatform/fluent-plugin-google-cloud/blob/e2f60cdd1d97e79ffe4e91bdbf6bd84837f27fa5/lib/fluent/plugin/out_google_cloud.rb#L1539
	b = strconv.AppendFloat(b, d.Seconds(), 'f', 9, 64)
	b = append(b, 's')
	return b
}