+
+## We set the path for the figures globally below, so if we want to
+## customize it for individual episodes, we can append a prefix to the
+## global path. For instance, if we call knitr_fig_path("01-") in the
+## first episode of the lesson, it will generate the figures in
+## `fig/rmd-01-`
+knitr_fig_path <- function(prefix) {
+ new_path <- paste0(opts_chunk$get("fig.path"),
+ prefix)
+ opts_chunk$set(fig.path = new_path)
+}
+