<_description>
A Klein bottle is the 4D analog of a moebius strip.
You can walk on the surface of the bottle or rotate it in 4D or walk
on it while it rotates in 4D. Inspired by Thomas Banchoff's book
"Beyond the Third Dimension: Geometry, Computer Graphics, and Higher
Dimensions", Scientific American Library, 1990.
https://en.wikipedia.org/wiki/Klein_bottle
Written by Carsten Steger; 2008.