code: func (api *PublicDebugAPI) SeedHash(ctx context.Context, number uint64) (string, error) {
  	block, _ := api.b.BlockByNumber(ctx, rpc.BlockNumber(number))
  	if block == nil {
  		return "", fmt.Errorf("block #%d not found", number)
  	}
  	return fmt.Sprintf("0x%x", ethash.SeedHash(number)), nil
  }
docs: // SeedHash retrieves the seed hash of a block.