def firstId(self):
        """ Children passage

        :rtype: str
        :returns: First children of the graph. Shortcut to self.graph.children[0]
        """
        if self._first is False:
            # Request the next urn
            self._first = self.getFirstUrn()
        return self._first
Children passage

        :rtype: str
        :returns: First children of the graph. Shortcut to self.graph.children[0]