code: def geo_point_n(arg, n):
      
      op = ops.GeoPointN(arg, n)
      return op.to_expr()
docs: Return the Nth point in a single linestring in the geometry.
      Negative values are counted backwards from the end of the LineString,
      so that -1 is the last point. Returns NULL if there is no linestring in
      the geometry
  
      Parameters
      ----------
      arg : geometry
      n : integer
  
      Returns
      -------
      PointN : geometry scalar