== foo ==
fun foo() {
    x = ""
}
---------------------
L0:
  1 <START>
  2 mark({ x = "" })
    magic[UNRESOLVED_CALL](x) -> <v0>
    magic[VALUE_CONSUMER](x|<v0>) -> <v1>
    mark("")
    r("") -> <v2>
    w(x|<v2>)
L1:
  1 <END>                                    NEXT:[<SINK>]
error:
    <ERROR>                                  PREV:[]
sink:
    <SINK>                                   PREV:[<ERROR>, <END>]
=====================