state: add environment persistency with UUID

trivial/uuid.go

 package trivial
 
 import (
         "crypto/rand"
         "fmt"
         "io"
 )
 
 // UUID represent a universal identifier with 16 octets.
 type UUID [16]byte
 
 // NewUUID generates a new version 4 UUID relying only on random numbers.
 func NewUUID() (UUID, error) {
         uuid := UUID{}
         if _, err := io.ReadFull(rand.Reader, []byte(uuid[0:16])); err != nil {
                 return UUID{}, err
         }
         // Set version (4) and variant (2) according to RfC 4122.
         var version byte = 4 << 4
         var variant byte = 8 << 4
         uuid[6] = version | (uuid[6] & 15)
         uuid[8] = variant | (uuid[8] & 15)
         return uuid, nil
 }
 
 // Copy returns a copy of the UUID.
 func (uuid UUID) Copy() UUID {
-        raw := uuid.Raw()
-        return UUID(raw)
+        uuidCopy := uuid
+        return uuidCopy
 }
 
 // Raw returns a copy of the UUID bytes.
 func (uuid UUID) Raw() [16]byte {
-        var raw [16]byte
-        copy([]byte(raw[0:16]), []byte(uuid[0:16]))
-        return raw
+        return [16]byte(uuid)
 }
 
 // String returns a hexadecimal string representation with
 // standardized separators.
 func (uuid UUID) String() string {
         return fmt.Sprintf("%x-%x-%x-%x-%x", uuid[0:4], uuid[4:6], uuid[6:8], uuid[8:10], uuid[10:16])
 }