{
  "name": "angle_at_vertex",
  "type": "function",
  "description": "Returns the bisector angle (average angle) to the geometry for a specified vertex on a linestring geometry. Angles are in degrees clockwise from north.",
  "arguments": [ {"arg":"geometry","description":"a linestring geometry"},
                 {"arg":"vertex","description":"vertex index, starting from 0; if the value is negative, the selected vertex index will be its total count minus the absolute value"}],
  "examples": [ { "expression":"angle_at_vertex(geometry:=geom_from_wkt('LineString(0 0, 10 0, 10 10)'),vertex:=1)", "returns":"45.0"}]
}