NewEntry returns a new cache entry it doesn't sets the expiresAt & the response because these are setting each time on Reset.

ParseMaxAge parses the max age from the receiver parameter, "cache-control" header returns seconds as int64 if header not found or parse failed then it returns -1.

Entry is the cache entry contains the expiration datetime and the response.

Response is the cached response will be send to the clients its fields setted at runtime on each of the non-cached executions non-cached executions = first execution, and each time after cache expiration datetime passed.

LifeChanger is the function which returns a duration which will be compared with the current entry's (cache life) duration and execute the LifeChanger func to set the new life time.