concatenate xmls in list to one xml

Question

I have list of xmls files each item has xml string, I would like to concatenate all xmls in list to one xml.

for e.g.

 

XML 1:

 <catalog>

   <book id="bk101">

   <author>Gambardella, Matthew</author>

   <title>XML Developer's Guide</title>

   <genre>Computer</genre>

   <price>44.95</price>

  </book>

</catalog>

 

XML 2:

<catalog>

   <book id="bk102">

   <author>Ralls, Kim</author>

   <title>Midnight Rain</title>

   <genre>Fantasy</genre>

   <price>5.95</price>

   </book>

</catalog>

 

 Result needed xml1 and xml2 concatenate to one :

 

<?xml version="1.0"?>

<catalogs>

   <catalog>

      <book id="bk101">

      <author>Gambardella, Matthew</author>

      <title>XML Developer's Guide</title>

      <genre>Computer</genre>

      <price>44.95</price>

      </book>

   </catalog>

   <catalog>

      <book id="bk102">

      <author>Ralls, Kim</author>

      <title>Midnight Rain</title>

      <genre>Fantasy</genre>

      <price>5.95</price>

      </book>

   </catalog>

</catalogs>

 

 Thanks