A Common-Sense Guide to Data Structures and Algorithms in Python, Volume 1: Exercise refers to non-existent includes method

Title: A Common-Sense Guide to Data Structures and Algorithms in Python, Volume 1: no includes method present (p 225)

@jaywengrow

In the Exercises section of Chapter 13, Exercise 2 (page 225) has the following text:

Here’s an implementation that is O(N^2) (the includes method alone is already O(N), since the computer needs to search the entire array to find n):

The example code in the exercise does not have an includes method, nor is that a Python built-in; the example code does have the Python for variable in construct, which is what I think is being referred to here.

Perhaps this is an artifact of re-implementing the exercise in Python from a different language or pseudocode.