> For the complete documentation index, see [llms.txt](https://backend-course.cornellappdev.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://backend-course.cornellappdev.com/chapters/abstractions.md).

# 4. Abstractions

{% content-ref url="/pages/-M1xJkliyd9c8vw7q8DG" %}
[Pre-Class TODO's](/chapters/abstractions/pre-class.md)
{% endcontent-ref %}

{% content-ref url="/pages/-Lu9fmEVuq40C5o\_1gnW" %}
[Lecture](/chapters/abstractions/lecture.md)
{% endcontent-ref %}

{% content-ref url="/pages/-Lu9fo8cGft84tt4ILwt" %}
[Demo](/chapters/abstractions/demo.md)
{% endcontent-ref %}

{% content-ref url="/pages/-Lu9fpn\_XYbqaje0xKLH" %}
[Assignment Handout](/chapters/abstractions/handout.md)
{% endcontent-ref %}

{% content-ref url="/pages/-Luj-KDcRkUl9PvXY4R4" %}
[API Specification](/chapters/abstractions/api.md)
{% endcontent-ref %}