Returns a Supplier object for the array.
The supplier allows you to iterate over the index/item pairs
of the array.
The supplier enumerates the array items in their sequenced order.
For multi-dimensional Arrays, the supplier index method will return the
index values as an array of index numbers.
Example 5.190. Array class — supplier method
a=.array~of("Fred","Mike","David")sup=a~suppliera~append("Joe")dowhilesup~availablesaysup~item-- displays "Fred", "Mike", and "David"sup~nextend
