Smooth wiggling of the arm without stopping

[Arth4s]

Hello, I have a question, how to correctly make a smooth wiggling for example, as in my case hand and fingers, without stopping? (I have attached an example of how I would like to do)

https://youtu.be/aRHncsjW1VY

[Arth4s]

Also attached a screenshot of how I tried to do it 

[Rick Gerard · Accepted solution]

You can use loopOut() expressions to create smooth oscillations if the first and last keyframes are identical. You can pre-compose a looping motion and then use Time Remapping to change the speed and slow the movement down or speed it up without causing duplicate frames.