code: func (txRwSet *TxRwSet) ToProtoBytes() ([]byte, error) {
  	var protoMsg *rwset.TxReadWriteSet
  	var err error
  	if protoMsg, err = txRwSet.toProtoMsg(); err != nil {
  		return nil, err
  	}
  	return proto.Marshal(protoMsg)
  }
docs: /////////////////////////////////////////////////////////////////
  // FUNCTIONS for converting messages to/from proto bytes
  /////////////////////////////////////////////////////////////////
  // ToProtoBytes constructs TxReadWriteSet proto message and serializes using protobuf Marshal