why did he label the axes to weirdly? Why did he use z for the vertical axe when he could have just used y to avoid confusion?####[['NULL', 'Instructor', 'NEG'], ['axes', 'Teaching_Setup', 'NEG'], ['z', 'Mathematical_Related_Concept', 'NEU'], ['vertical axe', 'Mathematical_Related_Concept', 'NEU'], ['y', 'Mathematical_Related_Concept', 'NEU']]