Object url
if (url == null) {
  try {
    url = null // Warning is here
  } catch (Exception e) {
    throw new RuntimeException(e)
  }
 }
return url
-----
0(1) element: null
1(2) element: IF statement
2(3,10) READ url
3(4) element: Open block
4(11) WRITE url
5(6) element: Catch clause
6(7) WRITE e
7(8) READ e
8(9) ARGUMENT element: Reference expression
9(13) THROW. element: THROW statement
10(11) End element: IF statement
11(12) READ url
12(13) element: RETURN statement
13() element: null