'Get the latest live departure data for the specified stop.'

def _update(self):

    params = {'darwin': 'false', 'calling_at': self._calling_at, 'train_status': 'passenger'}
    self._do_api_request(params)
    self._next_trains = []
    if (self._data != {}):
        if (self._data['departures']['all'] == []):
            self._state = 'No    departures'
        else:
            for departure in self._data['departures']['all']:
                self._next_trains.append({'origin_name': departure['origin_name'], 'destination_name': departure['destination_name'], 'status': departure['status'], 'scheduled': departure['aimed_departure_time'], 'estimated': departure['expected_departure_time'], 'platform': departure['platform'], 'operator_name': departure['operator_name']})
            self._state = min(map(_delta_mins, [train['scheduled'] for train in self._next_trains]))
