docs: def get_all_stations(self, station_type=None):
          """Returns information of all stations.
          @param<optional> station_type: ['mainline', 'suburban', 'dart']
          """
          params = None
          if station_type and station_type in STATION_TYPE_TO_CODE_DICT:
              url = self.api_base_url + 'getAllStationsXML_WithStationType'
              params = {
                  'stationType': STATION_TYPE_TO_CODE_DICT[station_type]
              }
          else:
              url = self.api_base_url + 'getAllStationsXML'
  
          response = requests.get(
              url, params=params, timeout=10)
  
          if response.status_code != 200:
              return []
  
          return self._parse_station_list(response.content)