AnySizeBearing - roller bearing/ball bearing fully parametrized

https://www.thingiverse.com/thing:2746804 is a nice idea. Thus I remodeled it in OpenSCAD to get a fully parametrized version.
As the name AnySizeBearing promises, it lets you create a roller bearing with any inner and outer diameter, di, da and any height h. OK, there is some restriction in the code that enforces a minimal height and a minimal distance between the inner and outer diameter.
The call is simple. You specify the three measures and that's it:
bearing(da=40, di=11.7, h=12); // single unit
To simplify usage, the code automatically stacks up several instances, if the height is not representable by a single stage design. Further it also calculates the number and the radius of the rollers. Also note that I implemented a help_AnySizeBearing() function.
To test the code, I made a printout using a 0.5mm nozzle and 0.2mm layers. It came out well: see the video