NOTE: This is wrong. It checks `this.x ?? x` but `x` should have precedence over `this.x` since it was defined later!

module.exports = function ({
  builtins,
  $$jsNix$extend
}) {
  return {
    "const_": function () {
      return x => {
        return _ => {
          return (this?.x ?? x)();
        };
      };
    },
    "a": function () {
      return (this?.const_ ?? const_)()(1)((this?.a ?? a)());
    }
  }.a();
};