$[70$ points$]$ This problem has two parts. In the first part, you have to hand$-$execute a recursive function and in the second part, you have to complete some partial code.

$($a$)$ What output from the print statements does the following function call produce: mergeSort $($L$,3,7$ when $L=[10,11,2,9,1,4,8,2,12,1,15]?$

Separately, write down what $L$ is after the call mergeSort $(L,3,7).$