code: func (qs *queryServer) GetBlockHeader(ctx context.Context, param *GetBlockParam) (*types.Header, error) {
  	header, err := qs.blockchain.GetBlockHeader(param.Height)
  	if err != nil {
  		return nil, err
  	}
  	abciHeader := tmtypes.TM2PB.Header(header)
  	return &abciHeader, nil
  }
docs: // Tendermint and blocks