D = path (D, P) appends the geom.Path P, open or closed, its straight segments, arcs and splines kept as they are. A path is what joins a spline to the lines and arcs around it, so a profile of all three is drawn as one entity:

 P = join (geom.Path ([0, 0; 20, 0]), ...
           geom.Spline ([20, 0; 35, 10; 50, 5]));
 D = draw.Drawing ().path (P);

A drawing is flat, so P must lie in its xy plane, whatever its geom.UCS; the drawing keeps the same path, re-expressed in its own coordinates.

See also: geom.Path, polyline, spline

Source Code: draw.Drawing