Closed Unassigned: Difficult to use body of mutually recursive functions [75]

"assume R; assert body_of_R;" fails in lemma L1 below.

```
predicate R1(x:int, y:int) { x > 0 ==> R2(x - 1) }
predicate R2(x:int) { exists y :: R1(x, y) }

lemma L1(x:int)
{
assume R2(x);
assert exists y :: R1(x, y); // FAILS
}

lemma L2(x:int)
requires R2(x); // Oddly, adding this requires fixes the problem
{
assume R2(x);
assert exists y :: R1(x, y); // SUCCEEDS
}
```