code: def create_free_space_request_content():
          
          root = etree.Element('propfind', xmlns='DAV:')
          prop = etree.SubElement(root, 'prop')
          etree.SubElement(prop, 'quota-available-bytes')
          etree.SubElement(prop, 'quota-used-bytes')
          tree = etree.ElementTree(root)
          return WebDavXmlUtils.etree_to_string(tree)
docs: Creates an XML for requesting of free space on remote WebDAV server.
  
          :return: the XML string of request content.