Compare piped code at the same level

[gadenbuie]

For exercises like

# user code
a %>% b()

# solution code
a %>% b() %>% c() %>% d()

the graded code that's compared is b(a) vs d(c(b(a)) and the outer calls of the user code are compared to the inner calls of the solution.

This results in

I expected d() where you wrote b()

which jumps the user to the end rather than providing feedback about their next step. I haven't explored how feasible it is, but it would be good to try to notice the extra levels of functions calls when comparing to be able to report

I expected you to call c()

[garrettgman]

+ 1

It'd be great to also recast the message as a %>% hint if we spot that they are using %>%, e.g.

I expected you to add `%>% c()` after you called `b()`.