Original documentation at http://micropython-is31fl3731.readthedocs.io/
Trivially modified to add support for the 7x17 matrix built into the ELECFREAKS Pico:ed:
from machine import I2C
import is31fl3731
i2c = I2C(1) # scl=19, sda=18
display = is31fl3731.PicoEd(i2c)
display.fill(127)