Loc class structure:
~~~~~~~~~~~~~~~~~~~~~
create class Loc
  export:
  var Row     //3
  var Col     //4
  method New=LocNew   //o:New() --> self
  method Init=LocInit //o:Init(Row,Col) --> true
  method Get=LocGet   //o:Get() --> true
  method Set=LocSet   //o:Set() --> true
  endclass