 
      
      queueProvides Queue data type
class queueThis class does not inherit to any class.
construct() — The constructor. Create an instance of class queue        getsize() — Get the size of the Queue        isempty() — Check whether the size of the Queue is empty or not        makeempty() — Make the Queue empty        pop() — Retrieve and remove the head of the Queue, or return nothing if the Queue is empty        push() — Insert a new element into the Queue        toarray() — Create an array containing all of the elements in the Queue        top() — Retrieve but not remove the head of the Queue, or return nothing if the Queue is empty