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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _check_expiration(self, url: str, data: 'SavedEndpoint') -> 'SavedEndpoint': """Checks the expiration time for data for a url. If the data has expired, it is deleted from the cache. Args: url: url to check data: page of data for that url Returns: value of either the passed data or None if it expired """

        if data.expires_after < time.time():
            del self.data[url]
            data = None
        return data