<p>
If <code>list</code> pointed to a cyclic list,
then the original program would never access <code>*p</code> or <code>*q</code>,
but the rewritten program would.
(Moving `*p` ahead would be safe if the compiler can prove `*p` will not panic;
moving `*q` ahead would also require the compiler proving that no other
goroutine can access `*q`.)
</p>

<p>
Not introducing data races also means not assuming that called functions