code: func VisvalingamKeep(path *geo.Path, toKeep int) *geo.Path {
  	return Visvalingam(path, math.MaxFloat64, toKeep)
  }
docs: // VisvalingamKeep runs the Visvalingam-Whyatt algorithm removing
  // triangles of minimum area until we're down to `toKeep` number of points.
  // Returns a new path and DOES NOT modify the original.