new_contents: #!/usr/bin/env python
  
  import sys
  
  import lxml.etree
  
  def main():
      if len(sys.argv) < 3:
          sys.stderr.write('ERROR: Must provide at least 2 KML files to merge\n')
          sys.exit('Usage: {} FILE1 FILE2 ...'.format(sys.argv[0]))
      
      first_kml_root = lxml.etree.parse(sys.argv[1]).getroot()
      first_kml_ns = first_kml_root.nsmap[None]
      first_kml_document = first_kml_root.find('{{{}}}Document'.format(
              first_kml_ns))
      
      for filename in sys.argv[2:]:
          kml_root = lxml.etree.parse(filename).getroot()
          kml_ns = kml_root.nsmap[None]
          kml_document = kml_root.find('{{{}}}Document'.format(kml_ns))
          # Add the Document node's child elements to the first KML file
          for element in kml_document.iterchildren():
              first_kml_document.append(element)
              
          print(lxml.etree.tostring(
                  first_kml_root,
                  encoding='utf-8',
                  xml_declaration=True,
                  pretty_print=True,
          # .decode('utf-8') is required for Python 3
          ).decode('utf-8'))
  
  
  if __name__ == '__main__':
      main()
  
subject: Add script for merging KML files