Aliases: wk_vertices wk_coords wk_vertex_filter
Keywords:
### ** Examples wk_vertices(wkt("LINESTRING (0 0, 1 1)"))
<wk_wkt[2]> [1] POINT (0 0) POINT (1 1)
wk_coords(wkt("LINESTRING (0 0, 1 1)"))
feature_id part_id ring_id x y 1 1 1 0 0 0 2 1 1 0 1 1