add WithoutDashString() method

uuid.go

@@ -57,6 +57,10 @@ func (u *UUID) String() string {
 	return fmt.Sprintf("%x-%x-%x-%x-%x", u[0:4], u[4:6], u[6:8], u[8:10], u[10:])
 }
 
+func (u *UUID) WithoutDashString() string {
+	return fmt.Sprintf("%x", u[:])
+}
+
 func (u *UUID) variantRFC4122() {
 	u[8] = (u[8] & 0x3f) | 0x80
 }