code: def _get_mod_mtime(self, filepath):
          
          file_mtime = self.tramp.getmtime(filepath)        
          xmlpath = self.get_xmldoc_path(filepath)
          if self.tramp.exists(xmlpath):
              xml_mtime = self.tramp.getmtime(xmlpath)
              if xml_mtime > file_mtime:
                  file_mtime = xml_mtime
  
          return file_mtime
docs: Gets the modified time of the file or its accompanying XML file,
          whichever is greater.