guard​ ​let​ x = x { ... } ​// yes​
guard​ ​let​ y = x { ... } ​// no​

guard let data = data else{...}

func process(){
  data : AnyObject?

  if x == nil{ data = m}
  else if x > 5{ data = j}
  guard let data = data else { return } // Definition conflicts with previous value
  somefunc(data)
}