text: from floodsystem.stationdata import build_station_list
  from floodsystem.stationdata import update_water_levels
  
  stations = build_station_list()
  
  def risk(stations):
      update_water_levels(stations)
      severe = set()
      high = set()
      moderate = set()
      low = set()
      for station in stations:
          h = station.relative_water_level()
          if h is None:
              pass
          elif h > 2.0 and station.town is not None:
              severe.add(station.town)
          elif h > 1.5 and h < 2.0 and station.town is not None:
              high.add(station.town)
          elif h > 1.0 and h < 1.5 and station.town is not None:
              moderate.add(station.town)
          elif h < 1.0 and station.town is not None:
              low.add(station.town)
      return severe, high, moderate, low
  
  
  severe, high, moderate, low = risk(stations)
  
  print("Severe risk of flooding \n", severe)
  print("High risk of flooding \n", high)
  print("Moderate risk of flooding \n", moderate)
  print("Low risk of flooding \n", low)
  