Just a good-to-have function to add to power_Test class IMO.
Since MeasurementLogger and CheckpointLogger both have a checkblock function, and that the syntax for using checkblock function is more elegant than that for using checkpoint function, I think this may be a good thing to do.
Priority set to 3 as it's not critical.

reference (link to the checkblock functions):
https://cs.corp.google.com/chromeos_public/src/third_party/autotest/files/client/cros/power/power_status.py?rcl=f6ecba00284b9c03f61893251a4347ac01dad351&l=1613
https://cs.corp.google.com/chromeos_public/src/third_party/autotest/files/client/cros/power/power_status.py?rcl=f6ecba00284b9c03f61893251a4347ac01dad351&l=1441