>>>
class Bar {
  void foo() {
    blah.method(someLongArgument, andAnotherOne, andAThirdOne, andOneMore)
      .then((var x) {
        var y = x * 2;
      });
  }
}
<<<
class Bar {
  void foo() {
    blah.method(someLongArgument, andAnotherOne, andAThirdOne, andOneMore).then(
      (var x) {
        var y = x * 2;
      },
    );
  }
}