The first file, customTests.R is where you can specify your own functions for
testing the correctness of swirl questions.
We'll talk about answer testing a little bit later.
Dependson.txt is a text file that you can use to list
the names of functions, excuse me, the names of R packages that are on Cram.
That's where we'll check to make sure R installed before the lesson begins.
initLesson.R is an R script, and
whatever you write in that R script will happen before a lesson starts,
so you can load the data inside of initLesson.R or
you can create functions that will soon then be used in the lesson.
And then this lesson.yaml file is exactly what we're looking at here
inside of RStudio.
I like using RStudio for writing swirl lessons because having a text editor and
an R console next to each other on the same screen works for me.
I certainly recommend using RStudio but
different people have their different work flows.