* here's a cursed verification trace that fails:

```
thread 'main' panicked at netlist/src/design.rs:261:13:
verification failed!

design:
 %0:2 = input "i_insn"
 %2:2 = match %0:2 { 00 XX }
-%4:0 = output "m" %2:2
+%4:0 = output "m" { %_8 %_5 }
+%_5:1 = eq %0:2 00
+%_6:1 = eq %0:2 10
+%_7:1 = buf %0+0
+%_8:1 = or %_6 %_7

counterexample:
%0:2 = 1X
%2:2 = 10
%_5 = 0
%_6 = X
%_7 = X
%_8 = X

possible cause: replacing net %2+1 with net %_8 is not valid
```