anchor.diff:        next_state = VARIABLE_SET.generate_new_state_variable();
      }
   
  +   :
      (WS)* AG_OPERATOR_KW
         bl_formula[next_state]
      (WS)* R_PAREN
  
positive.code:    {
        /* TODO */
        $result =
           $bl_formula.forSome
           (
              next_state.in
              (
  
negative.code: ;
  
  bl_ex_operator [Variable current_state]
     returns [Formula result]
  
     @init
     {
  