Last week I made a video about adding call/cc to the interpreted language, and placed that video on Moodle.  
Today a student pointed out a small error in the code on that video.  
It is in the code added to apply-prim-proc, where there is a new call to apply-proc. 
The CPS version of apply-proc is supposed to take three arguments, and I only gave it two.  
The third argument, of course, is supposed to be a continuation, and the specific continuation that is supposed to go there is k.  
So k plays two roles here:  (1) THe continuation-proc that is passed to the receiver is constructed using k,
(2) k also is the continuation passed to apply-proc.  Think about the two situations in which each of these might be used.