code: func (t *TxStructure) HGetAll(key []byte) ([]HashPair, error) {
  	var res []HashPair
  	err := t.iterateHash(key, func(field []byte, value []byte) error {
  		pair := HashPair{
  			Field: append([]byte{}, field...),
  			Value: append([]byte{}, value...),
  		}
  		res = append(res, pair)
  		return nil
  	})
  
  	return res, errors.Trace(err)
  }
docs: // HGetAll gets all the fields and values in a hash.