This library has been deprecated and fully replaced with https://github.com/adafruit/Adafruit_NeoPixel which supports modern 800 KHz and 400 KHz (for most chipsets)
This Arduino library supports our original "V1" Flora Pixels ONLY. You can spot these by the small IC chip on the back of the board.
For all newer products -- "V2" Flora Pixels (no IC chip on the back), NeoPixel Stick, Flex Strip, etc. -- use the Adafruit_NeoPixel library: