def stations_highest_rel_level(stations, N):
    """For a list of MonitoringStaton objects (stations), returns a list of the N stations
    at which the water level, relative to the typical range, is highest"""

    #Filter list as to not include stations without relative water level
    new_stations = list(filter(lambda station: station.relative_water_level() is not None, stations))

    #Sorts stations in descending order of relative water level
    new_stations.sort(key=lambda station: station.relative_water_level(), reverse = True)

    #Return first N stations in lists (N stations with highest water level)
    return new_stations[:N]