code: def convexhull(data, col, fill=True, point_size=4):
      
      from geoplotlib.layers import ConvexHullLayer
      _global_config.layers.append(ConvexHullLayer(data, col, fill, point_size))
docs: Convex hull for a set of points
  
      :param data: points
      :param col: color
      :param fill: whether to fill the convexhull polygon or not
      :param point_size: size of the points on the convexhull. Points are not rendered if None