How to animate a 360° rotation of an armature bone

Have you ever tried to animate a bone making a complete turn in a regular rotations?
I recently had to model and animate a watch for a real-time experience using the GameEngine and came up with not being instantly able to animate a bone 360° rotation correctly over one minute (using Z-axis and keyframing). My lack of quaternions knowledge made me do a quick  google-search for an easy answer to “how to animate a bone rotation in blender?”. I had no success, so i investigated myself and after few minutes came with understanding a bit how quaternion rotation works, and here is what i wish i had found on google :
This is the curves of a bone rotating 360° during 20 frames.

fig 1. ipo curves of QuatRot for a full 360° rotation

First of all Quaterions always are beetween -1 and 1. Frame 0 would be my bone completely up at 0°. At frame 10, the break you can see is actually when it reaches 180° and needs to go back up, but continue turning, otherwise you would have the bone going backward to angle 0° instead of angle 360°

Below is a visualization of the curves of a bone going from 0 to 180° and back to 0°:

fig 2. 0° to 180° and back curve

 

And here would be a graph showing how to animate many turns, it is just a repetition of fig 1.

fig 3. Continuous bone rotations

Voila. I do hope it can help someone one day. It is a simple thing, but good to know, as sometimes bone rotations can be confusing. I might also have missed a great tutorial, i would be happy to add it here.
And let me know if it not very clear.