Fix implicit missings using complete()

We are going to explore a new dataset, frogger.

This dataset contains 4 scores per player recorded at different times: morning, afternoon, evening, and late_night.

Every player should have played 4 games, one at each of these times, but it looks like not every player completed all of these games.

Use the complete() function to make these implicit missing values explicit

100 XP

For the frogger dataset:

Use complete() from tidyr on the time variable to make implicit missing values explicit.