code: def check_response(response):
      
      if response.status_code < 200 or response.status_code > 300:
          raise ServerError('API requests returned with error: %s'
                            % response.status_code)
  
      try:
          response_text = loads(response.text)
      except ValueError:
          raise ServerError('The API did not returned a JSON string.')
  
      if not response_text:
          raise EmptyResponse()
  
      if 'failure' in response_text:
          if response_text['failure'] == 'Falscher Dateityp':
              raise UnsupportedFormat('Please look at picflash.org '
                                      'witch formats are supported')
          else:
              raise UnkownError(response_text['failure'])
docs: checks the response if the server returned an error raises an exception.