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: host.go
    path of file: ./repos/terratest/modules/docker
    
    the code of the file until where you have to start completion: package docker

import (
	"os"
	"strings"
)

// GetDockerHost returns the name or address of the host on which the Docker engine is running.
func GetDockerHost() string {
	return getDockerHostFromEnv(os.Environ())
}

func getDockerHostFromEnv(env []string) string {
	// 
    
func getDockerHostFromEnv(env []string) string {
	// Parses the DOCKER_HOST environment variable to find the address
	//
	// For valid formats see:
	// https://github.com/docker/cli/blob/6916b427a0b07e8581d121967633235ced6db9a1/opts/hosts.go#L69
	var dockerUrl []string

	for _, item := range env {
		envVar := strings.Split(item, "=")
		if len(envVar) == 2 && envVar[0] == "DOCKER_HOST" {
			dockerUrl = strings.Split(envVar[1], ":")
			break
		}
	}

	if len(dockerUrl) < 2 {
		// DOCKER_HOST was empty, not present or not a valid URL
		return "localhost"
	}

	switch dockerUrl[0] {
	case "tcp", "ssh", "fd":
		return strings.TrimPrefix(dockerUrl[1], "//")
	default:
		// if DOCKER_HOST is not in one of the formats listed above, return default
		return "localhost"
	}
}