If `swept_object` is a point list and there is no closure tag,
then `sweep`

connects `n`+1 successive copies of each
point (including the original) with straight line segments to form a
polyline. If there are m points in the original point list,
then m polylines with `n` segments each are formed by the
sweep. In this manner, `sweep`

forms a set of one-dimensional
objects (polylines) from zero-dimensional ones (points).

When there *is* a closure tag,
`sweep`

connects `n`
successive copies of each point (including the original) with straight
line segments and finally connects the last copy back to the original
to form a polygon with `n` sides. If there are m points in
the original point list, then m polygons with `n` sides
each are formed by the sweep. In this manner, `sweep`

forms a
set of two-dimensional objects (polygons) from zero-dimensional ones
(points).

Options
of the `sweep`

are copied directly to the resulting
polyline(s).