Fade?

#!/usr/bin/python3

from PWM import Pwm
from time import sleep

# Use for PWM on /dev/bone/pwm/
# see https://pastebin.com/R70P1wAn

led = Pwm('/dev/bone/pwm/1/b', frequency=50)

try:
    while True:
        for i in range(0, 10):
            led.value = i / 10
            sleep(0.2)
        for i in range(10, 0, -1):
            led.value = i / 10
            sleep(0.2)
except KeyboardInterrupt:
    print ("You have done it now!")
    LED.disable()