You've made it through the chapter on data!
We really got to the core of what D3 is about—that is, data wrangling. While learning about data wrangling, you saw some interesting properties of prime numbers, learned all about loading external data, and effectively used scales to avoid calculations. We played with promises and generators along the way.
Lastly, we made a cool map to learn how simple geographic data can be once you get a hand on a good source and transform it into a better format.