GC_ref and GC_unref are required when your Nim code needs to be responsible for
keeping track of memory, but you might end up passing things in and out of Nim
code. In general they aren't used a whole lot for regular C interop. The
important thing to keep in mind here is who is
_[allocating](https://forum.nim-lang.org/postActivity.xml#allocating) memory,
and who is responsible for
_[freeing](https://forum.nim-lang.org/postActivity.xml#freeing) memory. When
flex/bison passes you a cstring (actually a pointer to a buffer of characters,
char *), you need to look at their documentation to see if it is you or them
who should free it. If it's you, then you should import system/ansi_c and use
c_free to free this pointer. When you create the Argument return type it's a
similar story, not sure what flex/bison expects to get back but I assume a
pointer to a struct of some kind. If you are responsible for free-ing this then
you could use GC_ref before passing it to flex/bison, and then when you know
that it is done with it you can do GC_unref, but more likely is it that
flex/bison will free this when it's done with it. In that case you probably
need to use something like this:
nim
result = cast[ptr Argument](c_malloc(sizeof(Argument)))
Run
