// using "=="
bool _isFirstButton(int index, int length, TextDirection textDirection) {
  return index == 0 && ((direction == Axis.horizontal && textDirection == TextDirection.ltr) ||
    (direction == Axis.vertical && verticalDirection == VerticalDirection.down))
    || index == length - 1 && ((direction == Axis.horizontal && textDirection == TextDirection.rtl) ||
    (direction == Axis.vertical && verticalDirection == VerticalDirection.up));
}


// using a switch statement
bool _isFirstButton(int index, int length, TextDirection textDirection) {
  switch (direction) {
    case Axis.horizontal:
      return switch (textDirection) {
        TextDirection.rtl => index == length - 1,
        TextDirection.ltr => index == 0,
      };
    case Axis.vertical:
      return switch (verticalDirection) {
        VerticalDirection.up   => index == length - 1,
        VerticalDirection.down => index == 0,
      };
  }
}