<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _ParseLayerConfigJSON(self, parser_mediator, file_object):
 """Extracts events from a Docker filesystem layer configuration file. The path of each filesystem layer config file is: DOCKER_DIR/graph/<layer_id>/json Args: parser_mediator (ParserMediator):
 mediates interactions between parsers and other components, such as storage and dfvfs. file_object (dfvfs.FileIO):
 a file-like object. Raises: UnableToParseFile: when the file is not a valid layer config file. """

    file_content = file_object.read()
    file_content = codecs.decode(file_content, self._ENCODING)

    json_dict = json.loads(file_content)

    if 'docker_version' not in json_dict:
      raise errors.UnableToParseFile(
          'not a valid Docker layer configuration file, missing '
          '\'docker_version\' key.')

    if 'created' in json_dict:
      layer_creation_command_array = [
          x.strip() for x in json_dict['container_config']['Cmd']]
      layer_creation_command = ' '.join(layer_creation_command_array).replace(
          '\t', '')

      event_data = DockerJSONLayerEventData()
      event_data.command = layer_creation_command
      event_data.layer_id = self._GetIdentifierFromPath(parser_mediator)

      timestamp = timelib.Timestamp.FromTimeString(json_dict['created'])
      event = time_events.TimestampEvent(
          timestamp, definitions.TIME_DESCRIPTION_ADDED)
      parser_mediator.ProduceEventWithEventData(event, event_data)