Implementing weak references can be done like so: <https://github.com/nim-lang/Nim/blob/devel/tests/gc/weakrefs.nim>
Of course, there are other implementations possible, esp with destructors.
- Weak maps? aleclarson
- Weak maps? shirleyquirk
- Weak maps? cumulonimbus
- Weak maps? Araq
- Weak maps? planetis
