{
  "name": "is_closed",
  "type": "function",
  "description": "Returns true if a line string is closed (start and end points are coincident), or false if a line string is not closed. If the geometry is not a line string then the result will be null.",
  "arguments": [ {"arg":"geom","description":"a line string geometry"}],
  "examples": [ { "expression":"is_closed(geom_from_wkt('LINESTRING(0 0, 1 1, 2 2)'))", "returns":"false"},
                { "expression":"is_closed(geom_from_wkt('LINESTRING(0 0, 1 1, 2 2, 0 0)'))", "returns":"true"}]
}