I assume that the example code given on README.rst should be considered a "smoke test" or "hello world" program to enable the user to check that his/her display can be addressed and is basically working.
That said, with executing display.fill(0) it draws a black background on my black display. I didn't see any change at all.
I suggest to change this to display.fill(1) so it draws some other "color" than black on the display. At least this works for my SSD1306 OLED display.
Does that make sense?