Suppose we have a linked list implemented with the structure below. Write a function that will take in a

pointer to the head of a list and inserts a node storing $-1$ after each even value in the list. If the list is

empty or there are no even values in the list, no modifications should be made to the list. $($For example,

if the initial list had $2,6,7,1,3,$ and $8,$ the resulting list would have $2,-1,6,-1,7,1,3,8,-1.$