func NewV4() UUID {
	return global.NewV4()
}
NewV4 returns random generated UUID.
package uuid
import (
	"crypto/md5"
	"crypto/rand"
	"crypto/sha1"
	"encoding/binary"
	"hash"
	"net"
	"os"
	"sync"
	"time"
)
const epochStart = 122192928000000000
var (
	global = newDefaultGenerator()
	epochFunc = unixTimeFunc
	posixUID  = uint32(os.Getuid())
	posixGID  = uint32(os.Getgid())
)
func NewV1() UUID {
	return global.NewV1()
}
func NewV2(domain byte) UUID {
	return global.NewV2(domain)
}
func NewV3(ns UUID, name string) UUID {
	return global.NewV3(ns, name)
}