== foo ==
fun foo(x: Int) {
    val (a, b) = x
    a
}
---------------------
L0:
  1 <START>
    v(x: Int)
    w(x)
  2 mark({ val (a, b) = x a })
    r(x)
    v(a)
    w(a)
    v(b)
    w(b)
    r(a)
L1:
  1 <END>                         NEXT:[<SINK>]
error:
    <ERROR>                       PREV:[]
sink:
    <SINK>                        PREV:[<ERROR>, <END>]
=====================