take updated topic and repeat it
I'm wondering if there is a standard node for receiving a message, and then repeating the last message which was received on another topic at a specified rate. So something like what rostopic pub /topic std_msgs/String 'hi!' -r 10 does, except it would take the message it's sending from another topic that it is receiving from. This would seem like a useful node type to have, but I can't find it from my cursory search of the stacks.
Something like what relay does from the topic_tools stack.
My reason: I've set up the generic_teleop to work with a joystick and broadcast to a stageros on /robot_0/cmd_vel, but it stops when I am controlling it and don't move the joystick, I assume because it doesn't continually send messages, but only sends when there is an update to the joystick. Sticking my "repeat last message" node in between teleop_source_node and teleop_sink_twist_node (or between teleop_sink_twist_node and stageros) would solve this problem.
