Someone else's Machine Learning tutorial code

This puzzle was inspired by some tutorial code I downloaded from someone else’s GitHub. To protect the guilty, I have withheld the author’s name, paraphrased the relevant Python into pseudo-code and “removed the context”. I will only say the context has something to do with machine learning.

What message is represented by the following pseudo-code below and why?

NOTE: for purposes of this question please ignore the distinction between sets (unordered collection of objects) and strings (ordered set of characters, which may contain repeated letters).

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