Simulate the top$-$down version of merge sort on $a=($:$7,5,4,9,6,2,4$:$).$ Draw the tree structue

of the recursive calls of sort$\_$aux, and in each node specify the value of parameters $lo$ and

hi as well as the current value of $a$ at the end of the call. You do not need to specify the

steps inside the merge function.