Functions in Python documentation mentions "type-inference library" later in the tutorial but I can't find it

**Description of the issue**

In the ["Functions in Python documentation"](https://codeql.github.com/docs/codeql-language-guides/functions-in-python/), I see:

> In a later tutorial we will see how to use the type-inference library to find calls to the built-in function eval regardless of name of the variable called.

I don't see where the "type-inference library" is referenced later in the tutorial. In fact, I can't find this library in the documentation at all.