code: @Override
    public Long hdel(final byte[] key, final byte[]... fields) {
      checkIsInMultiOrPipeline();
      client.hdel(key, fields);
      return client.getIntegerReply();
    }
docs: Remove the specified field from an hash stored at key.
  <p>
  <b>Time complexity:</b> O(1)
  @param key
  @param fields
  @return If the field was present in the hash it is deleted and 1 is returned, otherwise 0 is
  returned and no operation is performed.