def edges(self, etype, order=None):
        """Return all the edges

        Parameters
        ----------
        etype : int
            Edge type
        order : string
            The order of the returned edges. Currently support:

            - 'srcdst' : sorted by their src and dst ids.
            - 'eid'    : sorted by edge Ids.
            - None     : the arbitrary order.

        Returns
        -------
        Tensor
            The src nodes.
        Tensor
            The dst nodes.
        Tensor
            The edge ids.
        """
        if order is None:
            order = ""
        elif order not in ["srcdst", "eid"]:
            raise DGLError(
                "Expect order to be one of None, 'srcdst', 'eid', "
                "got {}".format(order)
            )
        edge_array = _CAPI_DGLHeteroEdges(self, int(etype), order)
        src = F.from_dgl_nd(edge_array(0))
        dst = F.from_dgl_nd(edge_array(1))
        eid = F.from_dgl_nd(edge_array(2))
        return src, dst, eid
Return all the edges

        Parameters
        ----------
        etype : int
            Edge type
        order : string
            The order of the returned edges. Currently support:

            - 'srcdst' : sorted by their src and dst ids.
            - 'eid'    : sorted by edge Ids.
            - None     : the arbitrary order.

        Returns
        -------
        Tensor
            The src nodes.
        Tensor
            The dst nodes.
        Tensor
            The edge ids.
        
python/dgl/heterograph_index.py