Ok, so I realized my Mac was unziping the .zip file automatically... so it looked like a direct single .py file in my downloads directory.
I guess before May 8, all of the samples were single files.
I went back into my trash and found that the .zip file did indeed only have a single file, DigitalInput.py, which did also have the import reference in the code to PhidgetHelperFunctions.
I did some sleuthing and found that .zip version here (20180508):https://www.phidgets.com/downloads/phid ... Python_Ex/
I see that it was updated a day after so I guess I downloaded it at just the wrong moment after the sample code had been updated but before the PhidgetHelperFunctions.py was added.
Anyway, thanks for clarifying.