How to use inherited Object type as return type?

[janAkali]

Procedure calls must use `=` with [named 
arguments](https://nim-lang.org/docs/tut1.html#procedures-named-arguments) and 
not `:`, e.g.
    
    
    let animation: Animation = newAnimation(
        bitmapTableId = BitmapTableId.Flag,
        position = position,
        flip = if hFlip: kBitmapFlippedX else: kBitmapUnflipped,
        randomStartOffset = true
      )
    
    
    Run