anchor.diff:  #endif
     | Full
     | PdbOnly
  +  | Portable
     | NoDebug
   
   #if YAAF_FSHARP_SCRIPTING_PUBLIC
  
positive.code:       | _, StartsWith "--debug:" "pdbonly"
        | _, StartsWith "-g:" "pdbonly" ->
          { parsed with Debug = Some DebugMode.PdbOnly }, state
        | _, StartsWith "--debug:" "full"
        | _, StartsWith "-g:" "full"
        | _, FsiBoolArg "--debug" true
  
negative.code:       yield! maybeArgMap x.Debug (function
          | Full -> "--debug:full"
          | PdbOnly -> "--debug:pdbonly"
          | Portable -> "--debug:portable"
          | NoDebug -> "--debug-")
        yield! x.Defines
               |> Seq.map (sprintf "--define:%s")
  