Live streaming: check if manifest has been updated

AFAIK, for the Live streaming, it's required to reload manifest at least after 'target_duration' for the first time and if the manifest has not changed then it must wait for a period of one-half the target duration before retrying.

So, it would be great to have an ability to check if the manifest has been already updated (e.g. using previous content).
As another possible version, it might have any sense to add a function which returns the latest line(s) from the manifest to make it possible to compare the latest line from previous manifest and current.