function component(a, b) {
  let z = {
    a
  };
  (function () {
    z |> mutate(%);
  })();
  let y = z;
  {
    // z is shadowed & renamed but the lambda is unaffected.
    let z = {
      b
    };
    y = {
      y,
      z
    };
  }
  return y;
}