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: cmd.go
    path of file: ./repos/go-gin-example/vendor/github.com/Unknwon/com
    
    the code of the file until where you have to start completion: // +build go1.3

// Copyright 2013 com authors
//
// Licensed under the Apache License, Version 2.0 (the "License"): you may
// not use this f
    
func ExecCmdDirBytes(dir, cmdName string, args ...string) ([]byte, []byte, error) {
	bufOut := new(bytes.Buffer)
	bufErr := new(bytes.Buffer)

	cmd := exec.Command(cmdName, args...)
	cmd.Dir = dir
	cmd.Stdout = bufOut
	cmd.Stderr = bufErr

	err := cmd.Run()
	return bufOut.Bytes(), bufErr.Bytes(), err
}