code: def index_of_nearest(p, hot_points, distance_f=distance):
      
      min_dist = None
      nearest_hp_i = None
      for i, hp in enumerate(hot_points):
          dist = distance_f(p, hp)
          if min_dist is None or dist < min_dist:
              min_dist = dist
              nearest_hp_i = i
      return nearest_hp_i
docs: Given a point and a set of hot points it found the hot point
      nearest to the given point. An arbitrary distance function can
      be specified
      :return the index of the nearest hot points, or None if the list of hot
              points is empty