code: func (r DouglasPeuckerReducer) GeoReduce(path *geo.Path) *geo.Path {
  	factor := geo.MercatorScaleFactor(path.Bound().Center().Lat())
  	merc := path.Clone().Transform(geo.Mercator.Project)
  	reduced := DouglasPeucker(merc, r.Threshold*factor)
  
  	return reduced.Transform(geo.Mercator.Inverse)
  }
docs: // GeoReduce runs the DouglasPeucker on a lng/lat path.
  // The threshold is expected to be in meters.