concatenate

Implement a method which takes two LinkedIntLists as input and returns a new list containing all the items of the first followed by all the items of the second. Don$$t modify the input lists; use the new keyword to create new objects instead. Your implementation should run in linear time i$.$e$.$ without the use of nested for$-$loops.

list$1$: front $->1->2->3->/$

list$2$: front $->4->5->6->/$

If you made the call concatenate$($list$1,$ list$2),$ then it should return a new list:

return: front $->1->2->3->4->5->6->/$

and list$1$ and list$2$ would remain unchanged:

list$1$: front $->1->2->3->/$

list$2$: front $->4->5->6->/$