code: def gen_cumulative_distances(stops):
      
      stops[0]['d'] = 0.0
      for i in range(1, len(stops)):
          stops[i]['d'] = stops[i-1]['d'] + wgs84_distance(
              stops[i-1]['lat'], stops[i-1]['lon'],
              stops[i]['lat'], stops[i]['lon'],
              )
      for stop in stops:
          stop['d'] = int(stop['d'])
docs: Add a 'd' key for distances to a stop/shape-sequence.
  
      This takes a shape-sequence or stop-sequence, and adds an extra
      'd' key that is cumulative, geographic distances between each
      point. This uses `wgs84_distance` from the util module.  The
      distances are in meters.  Distances are rounded to the nearest
      integer, because otherwise JSON size increases greatly.
  
      Parameters
      ----------
      stops: list
          elements are dicts with 'lat' and 'lon' keys
          and the function adds the 'd' key ('d' stands for distance)
          to the dictionaries