Consistent function names

Fixes #790

iteration.Rmd

@@ -938,9 +938,9 @@ vs <- list(
 vs %>% reduce(intersect)
 ```
 
-The reduce function takes a "binary" function (i.e. a function with two primary inputs), and applies it repeatedly to a list until there is only a single element left.
+`reduce()` takes a "binary" function (i.e. a function with two primary inputs), and applies it repeatedly to a list until there is only a single element left.
 
-Accumulate is similar but it keeps all the interim results. You could use it to implement a cumulative sum:
+`accumulate()` is similar but it keeps all the interim results. You could use it to implement a cumulative sum:
 
 ```{r}
 x <- sample(10)