Flagging for No records found?

I am trying to implement some logic to see if my XSL code found, and then
displayed, any records. Try as I may I cannot find a clean way to do this. I
cannot set a flag, nor can I increment a count when I find a record so I
don't know how else to trap this. If no records meet the criteria then I'd
simply like to output a 'No Records Found' message.

The code below is an extract from the XSL, if I don't display any results
then at the end I want to print 'No records found'.

Any ideas? Thanks!

  <xsl:template match="/">

     <xsl:for-each select="xdql/object/content/content_chunk">

      <xsl:sort select="content_link"/>

      <xsl:choose>

       <xsl:when test="((product = $product) or ($product = 'All'))">

         <!-- I need to know if I ever got here .... -->

           <a>
            <xsl:attribute name="href"><xsl:value-of
select="content_link/@ref"/></xsl:attribute>
            <xsl:value-of select="content_link"/>
           </a>

           <br/>


       </xsl:when>
      </xsl:choose>

     </xsl:for-each>

     <!-- Print 'no records found' if nothing passed the ;when


  </xsl:template>




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