{
  "name": "is_valid",
  "type": "function",
  "description": "Returns true if a geometry is valid; if it is well-formed in 2D according to the OGC rules.",
  "arguments": [ {"arg":"geom","description":"a geometry"}],
  "examples": [ { "expression":"is_valid(geom_from_wkt('LINESTRING(0 0, 1 1, 2 2, 0 0)'))", "returns":"true"},
                { "expression":"is_valid(geom_from_wkt('LINESTRING(0 0)'))", "returns":"false"}]
}