Add feedback when T is used as TRUE or F as FALSE

[Laura-Puckett]

For exercises where the learner is expected to use TRUE or FALSE, it would be great if some specific feedback was automatically provided when they use T or F instead.

In the below example, the feedback from the wrong answer (using grade_this() or grade_this_code()) is currently:

In sum(car_parts_qty, na.rm = T), I expected na.rm = TRUE where you wrote na.rm = T.

I think this leaves a little room for confusion where a learner may not realize T and TRUE are actually different and they might assume it was a bug in the grading.

I think it'd be more clear if the automatic feedback mentions something along the lines of:

T should not be used in place of TRUE because T is mutable, and thus not the same as TRUE.

setup

car_parts_qty <- sample(1:50, 10, replace = TRUE)

expected solution

sum(car_parts_qty, na.rm = TRUE)

wrong answer

sum(car_parts_qty, na.rm = T)