During a previous call, the maximum number of items that can be returned is
the value specified in maxResults. If there more items in the
list, then a unique string called a nextToken is returned. To get the
next batch of items in the list, call this operation again, adding the next
token to the call. To get all of the items in the list, keep calling this
operation with each subsequent next token that is returned, until no more
next tokens are returned.