How to use the rosbag.parseMessageDefinition function in rosbag

connections.forEach((connection) => {
    const connectionTypes = parseMessageDefinition(connection.messageDefinition);
    connectionTypes.forEach(({ name, definitions }, index) => {
      // The first definition usually doesn't have an explicit name,
      // so we get the name from the connection.
      if (index === 0) {
        datatypes[connection.type] = definitions;
      } else if (name) {
        datatypes[name] = definitions;
      }
    });
  });
  return datatypes;