void addFirst(int i, obj) :This method adds the element obj at the first position of the linked list.
void addLast(int i, obj) :
This method appends the specified element to the end of list.
element removeLast() :
This method removes the last element from the list and returns it.
element remove(int i) :
This removes an element at the specified position i in the linked list.
element getFirst() :
This method returns the first element from the list.
element getLast() :
This method returns the last element from the list.