Return label for given lang or any default

        :param lang: Language to request
        :return: Label value
        :rtype: Literal

def get_label(self, lang=None):
        """ Return label for given lang or any default

        :param lang: Language to request
        :return: Label value
        :rtype: Literal
        """
        x = None
        if lang is None:
            for obj in self.graph.objects(self.asNode(), RDFS.label):
                return obj
        for obj in self.graph.objects(self.asNode(), RDFS.label):
            x = obj
            if x.language == lang:
                return x
        return x