def geo_lines(self, edges):
        """
        Utility function to convert a list of edges into a list of
        :class:`openquake.hazardlib.geo.Line` instances.

        :param edge: a node describing an edge
        """
        lines = []
        for edge in edges:
            with context(self.fname, edge):
                coords = split_coords_3d(~edge.LineString.posList)
            lines.append(geo.Line([geo.Point(*p) for p in coords]))
        return lines