如何计算从包含另一个XQuery函数的xsl：for-each循环返回的结果数？

I have the following XML:

我有以下XML:

<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet type="text/xsl" href="/go.html?url=count-example.xsl"?>
<musiclist>
<mp3>
    <id>MP1003</id>
    <artist>Frank Sinatra</artist>
    <title>Fly Me To The Moon</title>
    <location path="home/music/sinatra/MP1008.mp3" />
</mp3>
<mp3>
    <id>MP1004</id>
    <artist>Frank Sinatra</artist>
    <title>New York, New York</title>
    <location path="home/music/sinatra/MP1004.mp3" />
</mp3>
<mp3>
    <id>MP1005</id>
    <artist>Frank Sinatra</artist>
    <title>Young At Heart</title>
    <location path="home/music/sinatra/MP1009.mp3" />
</mp3>
</musiclist>
<?xml ve