== foo ==
fun foo(a: Array<Int>) {
    a[0] += 1
}
---------------------
L0:
    <START>             NEXT:[v(a: Array<Int>)]    PREV:[]
    v(a: Array<Int>)    NEXT:[w(a)]                PREV:[<START>]
    w(a)                NEXT:[r(a)]                PREV:[v(a: Array<Int>)]
    r(a)                NEXT:[r(0)]                PREV:[w(a)]
    r(0)                NEXT:[call(a[0], get)]     PREV:[r(a)]
    call(a[0], get)     NEXT:[r(1)]                PREV:[r(0)]
    r(1)                NEXT:[call(+=, plus)]      PREV:[call(a[0], get)]
    call(+=, plus)      NEXT:[r(a)]                PREV:[r(1)]
    r(a)                NEXT:[r(0)]                PREV:[call(+=, plus)]
    r(0)                NEXT:[r(1)]                PREV:[r(a)]
    r(1)                NEXT:[call(a[0], set)]     PREV:[r(0)]
    call(a[0], set)     NEXT:[<END>]               PREV:[r(1)]
L1:
    <END>               NEXT:[<SINK>]              PREV:[call(a[0], set)]
error:
    <ERROR>             NEXT:[<SINK>]              PREV:[]
sink:
    <SINK>              NEXT:[]                    PREV:[<ERROR>, <END>]
=====================