code: func (pdb *BytesBrokerWatcherEtcd) Put(key string, data []byte, opts ...datasync.PutOption) error {
  	return putInternal(pdb.Logger, pdb.kv, pdb.lessor, pdb.opTimeout, key, data, opts...)
  }
docs: // Put calls 'Put' function of the underlying BytesConnectionEtcd.
  // KeyPrefix defined in constructor is prepended to the key argument.