var err error
until err == nil {
   check err = someFunc()
} else {
   //handle error
}

var err error
{
  check := func(){if !(err==nil) {goto ELSE} }
  err =someFunc; check();
  goto END_BLOCK
ELSE:
  // handle
END_BLOCK:
  // code after until block
}

var r result
var ok bool
until ok && r.Valid() {
   check v,ok := someMap[key] // check inserted here with both ok and r.Valid() evaluated; if r is nil - it should panic as in *if* construction
   check r.Update(someValue) // check evaluated here
   r.DoSomething() // no check evaluated
   check r.NoChage() // check inserted here even both *ok* and *r* are not changed - this is programmer's responsibility
} else {
  // handle situation
}

var a int
until a>1000 && a<2000 {
  for i:=10;i<20;i++{
     check a=i*i*i // this will break loop on i=13
  }
}