How to migrate tf data types such as Quaternion, Vector3, Transform to tf2?

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There is not much mentioned about tf2 datatypes on tf2_ros documentation at http://docs.ros.org/latest/api/tf2_ro... . While comparing to http://docs.ros.org/latest/api/tf/htm... , we don't have any data types mentioned. My C++ code has plenty of tf datatypes such as

 tf::Quaternion q(msg->pose[index].orientation.x,
                msg->pose[index].orientation.y,
                msg->pose[index].orientation.z,
                msg->pose[index].orientation.w);


 tf::Transform transform;

How will I migrate them to tf2_ros?