$//$ list: ptr to a linked list of Node $($each with int data, and Node $*$ next$)//$ Return the sum of all values in the list. $//$ You may assume that list is not NULL $//$ However, the list may be empty $($i$.$e$.$ list$->$head may be NULL$)11$ in which case your code should return O$.$ int sum$($LinkedList $*$ list$)\{//$ Code may assume that these assertions are true; $//$ so does not need to do error checking for these conditions. assert$($list $!=$NULL$)$; $//$ TODO: Insert code here to calculate and return $//$ sum of all values in list $($o if there are none$).$ return $-42$; $//$ STUB! Replace this line with correct code $---------$SUM$----$ FAILED: sum$($listi$)$ Expected: $73$ Actual: $-42$ FAILED: sum$($list$2)$ Expected: $-28$ Actual: $-42$ FAILED: sum$($list$3)$ Expected: $6$ Actual: $-42$ FAILED: sum$($list$4)$ Expected: $3$ Actual: $-42$