Most (all?) of the commenters here seemed to miss the entire point of this feature: "Create custom prompts We provide a few preset prompts to get you started:

Most (all?) of the commenters here seemed to miss the entire point of this feature: "Create custom prompts We provide a few preset prompts to get you started: three that explain what a particular block of code does, and another that generates example code for calling a function. You can customize the prompt and stop sequence of a query in order to come up with new applications that use Codex to interpret code. Creating these can feel like more of an art than a science! Small changes in the formulation of the prompt and stop sequence can produce very different results. The three different “explain” examples showcase strategies that tend to produce useful responses from the model, but this is uncharted territory! We’re excited to see what you use this for." This isn't for explaining code. That's just an example. This lets us create custom prompts for the OpenAI API using the codex model.