GC is thread-local. If you allocate a sequence or string or reference type in another thread you will segfault.
For temporaries you can use `setupForeignThreadGC()` and `teardownForeignThreadGc()`. If you need to merge partial results of GC-ed types I'm not sure but this thread might help: [https://forum.nim-lang.org/t/959](https://forum.nim-lang.org/t/959)
