def _concat_hetero_seeds(self, minibatch):
        """Concatenates the seeds into a single tensor in the hetero case."""
        seeds = minibatch._seed_nodes
        if isinstance(seeds, dict):
            (
                seeds,
                seed_offsets,
            ) = self.graph._convert_to_homogeneous_nodes(seeds)
        else:
            seed_offsets = None
        minibatch._seeds = seeds
        minibatch._seed_offsets = seed_offsets

        return minibatch
Concatenates the seeds into a single tensor in the hetero case.
python/dgl/graphbolt/impl/neighbor_sampler.py