def required_elements(element, *children):
for child in children:<EOL><INDENT>if element.find(child) is None:<EOL><INDENT>raise NotValidXmlException(msg_err_missing_children(element.tag, *children))<EOL><DEDENT><DEDENT>
Check element (``xml.etree.ElementTree.Element``) for required children, defined as XPath. Raise
    ``NotValidXmlException`` on error.

    :param element: ElementTree element
    :param children: list of XPaths to check
    :raises NotValidXmlException: if some child is missing