tweaks

docs/source/ch03_packaging.rst

@@ -59,11 +59,15 @@ Relative import
 ---------------
 When import a class / function within the same package, a ``relative import``
 should be used instead of ``absolute import``.
-An example is below (``top_level_interface.py``):
+An example is below (``api.py``):
+
+.. code-block:: python
+
+    from .flip_image import flip_image, read_test_image
+    from .demo import a_demo_function, ADemoClass
+
+    __all__ = ["flip_image", "read_test_image", "a_demo_function", "ADemoClass"]
 
-.. literalinclude:: ../../csst_proto/top_level_interface.py
-   :linenos:
-   :language: python
 
 .. note::
     Note the ``.`` means it's a relative import.