@classmethod
def _getChildText(cls, parent, childname):
    """ provides text of child named by childname

        :param parent: parent node
        :type parent: :class:`lxml.etree.Element`
        :param childname: child name
        :type childname: :opj:`str`
        :returns: text string
        :rtype: :obj:`str`
        """
    children = parent.findall(childname)
    return cls._getText(children[0]) if len(children) else None
