code: @Override
    public List<byte[]> mget(final byte[]... keys) {
      checkIsInMultiOrPipeline();
      client.mget(keys);
      return client.getBinaryMultiBulkReply();
    }
docs: Get the values of all the specified keys. If one or more keys don't exist or is not of type
  String, a 'nil' value is returned instead of the value of the specified key, but the operation
  never fails.
  <p>
  Time complexity: O(1) for every key
  @param keys
  @return Multi bulk reply