message: try to fix doctests
diff: @@ -775,7 +775,9 @@ pub fn set_screen_coordinates(context: &mut Context, rect: Rect) -> GameResult<(
  /// matrix by calling `param.into_matrix()` like so:
  ///
  /// ```
  -/// graphics::push_transform(param.into_matrix());
  +/// # use ggez::graphics;
  +/// # let param: graphics::DrawParam = Default::default();
  +/// graphics::push_transform(Some(param.into_matrix()));
  /// ```
  pub fn push_transform(context: &mut Context, transform: Option<Matrix4>) {
  let gfx = &mut context.gfx_context;
  @@ -801,6 +803,8 @@ pub fn pop_transform(context: &mut Context) {
  /// matrix by calling `param.into_matrix()` like so:
  ///
  /// ```
  +/// # use ggez::graphics;
  +/// # let param: graphics::DrawParam = Default::default();
  /// graphics::set_transform(param.into_matrix());
  /// ```
  pub fn set_transform(context: &mut Context, transform: Matrix4) {
  @@ -814,6 +818,8 @@ pub fn set_transform(context: &mut Context, transform: Matrix4) {
  /// matrix by calling `param.into_matrix()` like so:
  ///
  /// ```
  +/// # use ggez::graphics;
  +/// # let param: graphics::DrawParam = Default::default();
  /// graphics::transform(param.into_matrix());
  /// ```
  pub fn transform(context: &mut Context, transform: Matrix4) {
  