Hello World!
I'm talking about one aspect of animation.
And that's the idea that is you want something, a set of actions,
that's  going to repeat,
you want them to start and end in the same position.

I have a clown fish who's facing in the forward direction.
The first thing I'm going to do is have the clown fish turn to the left a 1/3 of a turn.
That's going to have him facing the right edge of the movie.
Next,  I'm going to have him move forward five for a duration of 10.
Turn left half a turn around so he's facing in the opposite direction.
Then he's going to move forward that same unit, 5.0, with a duration of 10.

If I then have him turn left half a turn, he'll be back where he started.
Let's run it. So, you can see he's moving forward,
turned around  a 1/2 turn,
and now he's moving forward 5,
so that he's right back where he started.
and then I had him turn around.
At this point here, he's at exactly the same position as when he started.
Right here.

The advantage of that is that I can make this a while loop.
while(true) and not this statement-
because  that's the one to get him oriented in the first place.
But all these statements are the ones I want him to repeat.
Make sure we get those in the right order.
Now when we run it, after turning to face the edge,
he moves across,  he turns around,  (which we don't see.)
He comes back, back to where he started, turns around.
He's going to do this again, and again, and again, forever.

If we want to have an animation occur inside the while,  and repeat endlessly,
we have to make sure that wherever we started is exactly the same position and orientation
as where it ends.