code: def get_trip_stop_coordinates(self, trip_I):
          
          query = """SELECT lat, lon
                      FROM stop_times
                      JOIN stops
                      USING(stop_I)
                          WHERE trip_I={trip_I}
                      ORDER BY stop_times.seq""".format(trip_I=trip_I)
          stop_coords = pd.read_sql(query, self.conn)
          return stop_coords
docs: Get coordinates for a given trip_I
  
          Parameters
          ----------
          trip_I : int
              the integer id of the trip
  
          Returns
          -------
          stop_coords : pandas.DataFrame
              with columns "lats" and "lons"