code: public double getPatternSpeed (String pattern_id, LocalDate date, LocalTime from, LocalTime to) {
  
          List<Trip> trips = getTripsForDate(pattern_id, date);
  
          return getAverageSpeedForTrips(trips, from, to);
      }
docs: Gets the pattern speed for a given pattern for a specified date and time window.
  @param pattern_id pattern ID
  @param date service date
  @param from beginning of time window
  @param to end of time window
  @return