'''
Mission 6: Heartbeat
Sample code
  - start with duplicating code for repeating, then
  using an infinite while loop. End with using two
  buttons to control the speed of the heartbeat.
  Code has a potential runtime error, since delay can
  go 0 or below. Loop remains infinite.
'''
from codex import *
from time import sleep

delay = 1

while True:
    # one heartbeat
    display.show(pics.HEART)
    sleep(delay)
    display.show(pics.HEART_SMALL)
    sleep(delay)

    if buttons.was_pressed(BTN_A):
        delay = delay + 0.2

    if buttons.was_pressed(BTN_B):
        delay = delay - 0.2