code: @Override
    public String rename(final byte[] oldkey, final byte[] newkey) {
      checkIsInMultiOrPipeline();
      client.rename(oldkey, newkey);
      return client.getStatusCodeReply();
    }
docs: Atomically renames the key oldkey to newkey. If the source and destination name are the same an
  error is returned. If newkey already exists it is overwritten.
  <p>
  Time complexity: O(1)
  @param oldkey
  @param newkey
  @return Status code repy