Consider the following multi$-$threaded pseudocode.lock$()$;unlock$()$;$\}$

channel$\_$non$\_$blocking$\_$recv$($channel$)\{$ channel$\_$recv$($channel$)$;$\}\}$Construct the best sequence of test code for exposing the bug in this code. That is$,$ the best

sequence of test code that will most likely exhibit the bug to the user.

Line $1$:

Line $2$:

Line $3$:

Line $4$: return TEST$\_$SUCCESS;