def METHOD_NAME(self, node_pairs, etype=None):
    """Generate negative pairs for a given etype form positive pairs
    for a given etype.
    Parameters
    ----------
    node_pairs : Tuple[Tensor, Tensor]
        A tuple of tensors that represent source-destination node pairs of
        positive edges, where positive means the edge must exist in the
        graph.
    etype : str
        Canonical edge type.
    Returns
    -------
    Tuple[Tensor, Tensor]
        A collection of negative node pairs.
    """
    raise NotImplementedError