Implement the insertAtPosition function of the LinkedList class .

bool LinkedList::insertAtPosition(int position, int d)

The job of this function is to insert a new node with given data d in the given position.

If position is less than 1 or greater than length + 1 then the function should leave the list unchanged and return false .

If given a legal position, the function will insert a new node with data d at that position and return true . For example, if the list is initially { 1, 2, 3 } and we call insertAtPosition(2, 20) then the list will be changed to { 1, 20, 2, 3 }.