code: def find_closest_weather(weathers_list, unixtime):
      
      if not weathers_list:
          return None
      if not is_in_coverage(unixtime, weathers_list):
          raise api_response_error.NotFoundError('Error: the specified time is ' + \
                                  'not included in the weather coverage range')
      closest_weather = weathers_list[0]
      time_distance = abs(closest_weather.get_reference_time() - unixtime)
      for weather in weathers_list:
          if abs(weather.get_reference_time() - unixtime) < time_distance:
              time_distance = abs(weather.get_reference_time() - unixtime)
              closest_weather = weather
      return closest_weather
docs: Extracts from the provided list of Weather objects the item which is
      closest in time to the provided UNIXtime.
  
      :param weathers_list: a list of *Weather* objects
      :type weathers_list: list
      :param unixtime: a UNIX time
      :type unixtime: int
      :returns: the *Weather* object which is closest in time or ``None`` if the
          list is empty