How to read a topic last value from a Python script?

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Hello.

I'm working on a teleop program in Python. I want to change a joint position and add an offset read from the keyboard.

So I need to read a topic value to add the offset and send the command with the target value. Of course I have read the tutorial about the subscriber in Python. My requirement is slightly different. I do not want to process a piece of code each time a value is published. I do not even need a fresh value, since I consider that the last published one is sufficient.

So is there a way to get this last published value using rospy?

Thanks for your help.