Polygonal lines in space

See Section 26.9.4 for polygonal lines in the plane.

The open_polygon command creates polygonal lines in space.

open_polygon takes S, a sequence of points.
open_polygon(S)returns and draws the polygon line whose vertices are the given points.

open_polygon(point(0,0,0),point(0,1,0),point(0,2,2),point(1,0,2))