Hi! I have a few questions about the code

[altctrl00]

First, I am confused by what the "popularity_model" in the main.py represents for ? Is it the base recommendation system in your implementation？if not, what's the base recommendation system in your code?
Second, Could you please clarify the dataset "career_builder_small_2" for better following?

Thanks

[altctrl00]

Third, what is the usage of "lambda_u" and "lambda_i" in "model.py"?