Grouping the values from a range index

grouping.xqy

xquery version "1.0-ml";
declare namespace sample = "http://marklogic.com/sample";
let $groupsize := 1000
let $values := cts:element-values(xs:QName("sample:value"))
let $count := fn:count($values)

let $groups :=
    for $i in (0 to (xs:int($count div $groupsize) + 1))
    let $group := $values[(($i * $groupsize) + 1) to (($i + 1) * $groupsize)]
    return fn:string-join($group, "|")

return (fn:count($groups), $groups)