dup : [a] Share a. a -> { p1 : a, p2 : a }#;
dup x = { p1 = x, p2 = x };

fun : [x]. x! -> Unit;
fun x = Unit;

test : [x]. x -> x;
test x = let! (x) a =
             let y = dup x
             in Unit
             end 
         in x 
         end;

badEscape : [x]. x -> x;
badEscape x = let! (x) a =
                let y = dup x
                in y.p1
                end 
              in x 
              end;


test2 : [a]. a -> a;
test2 x = let! (x) a = fun[a] x
          in x 
          end;