func Init()
  fvar(old)
  if(linked(Result) and linked(doStrCat))
    if(isdef(Extern))
      lng.decl_priv_var(s, 'string')
      if(isndef(Default))
        old = BLK_CREATE
      end 
    else
      lng.decl_loc_var(s, 'string')
      if(isndef(Default))
        old = LOC_HEAD
      end
    end
  end
  if(old)
    old = block.select(old)
    println(s, ' := ', Default, ';')
    block.select(old)
  end
end

func doStrCat
  if(linked(Result))
    println(s, ' := ', Str1 & Str2, ';')
    event(onStrCat, s)
  else
    event(onStrCat, Str1 & Str2)
  end
end

func Result
  if(linked(doStrCat))
    return(s)
  else
    return(Str1 & Str2)
  end
end