asclass VarContext {

  gettable VarContext parent;

  *() {}

  *(VarContext *parent) {}

  abstract O get(S name);

  abstract void set aka put(S name, O value);

  abstract AutoCloseable tempSet aka tempPut(S name, O value);

  // either undefines variable completely or just sets variable to null

  abstract void unset(S name);

  abstract MapSO varMap();

  void printMe {

    pnl(varMap());

    print(+parent);

  }

  // mechanism for returning from a script

  settable O exitFromScript;

  settable O returnValue;

  bool exiting() { ping(); ret exitFromScript != null; }

}