This library has been modified from the "Adafruit Neopixel Library" for use with Flutter microcontroller boards. Include Flutter_NeoPixel.h instead of Adafruit_NeoPixel.h and then use normally. Original library notes follow.
Arduino library for controlling single-wire-based LED pixels and strip such as the Adafruit 60 LED/meter Digital LED strip, the Adafruit FLORA RGB Smart Pixel, the Adafruit Breadboard-friendly RGB Smart Pixel, the Adafruit NeoPixel Stick, and the Adafruit NeoPixel Shield.
After downloading, rename folder to 'Adafruit_NeoPixel' and install in Arduino Libraries folder. Restart Arduino IDE, then open File->Sketchbook->Library->Adafruit_NeoPixel->strandtest sketch.