Is There Just a Learning Curve When You're Not Talking to Someone Other Than You?

There must be two person devices, like, I don't know, two person bicycles or something out there, where if two people get used to using this two person device together, then that's how they know how to use it. And maybe they would have a long learning curve to use that device by themselves or to go learn a different device that only take one person to useIt. To me, there are just, I can play tennis with somebody else, much harder for me to play tennis by myself. Like tennis, for example,. Then I put a wall up there to bounce the ball off of, right?