Re: Modify old code using new/finalizer to compile with gc:arc

[miran]

> when compileOption("gc", "arc") seems not to compile at all for old stable 
> Nim.

Wrap everything related to `arc` in the version check, e.g.:
    
    
    when (NimMajor, NimMinor) >= (1, 1):
      when compileOption("gc", "arc"):
         ....
    
    
    Run