Groovy sample application using a queue and linked list

Example with a queue:

def q = ["elem1", "elem2"] as Queue

q.offer("inserted string")
assert q.peek() == "elem1"
assert q.poll() == "elem1"
assert q.poll() == "elem2"
assert q.poll() == "inserted string"

Here is an example with a linked list:

def l = [1, 2, 3] as LinkedList
assert l[0] == 1
l.add(4)
assert l.last() == 4