Feedparser, no etag and modified attributes

How could I know if the feed has changed since last check if none of these attributes exists for a given feed ?Example with this one from a nintendo news website:

d=feedparser.parse('https://www.nintendolife.com/feeds/news')[In]:'modified' in d [Out]:False[In]:'etag' in d [Out]:False

Is my only possibility to check d.feed.published / d.feed.updated ?

Thanks in advance