Difinitely not the best way of doing it, but, like always, this
should work:
isMPressed = False
while True:
while button1_pressed() and button2_pressed():
print("do some")
while button3_pressed() and not isMPressed: # Only if it is pressed after button1 and button2 are pressed
isMPressed = False
print("do some2")
if button2_pressed() == 0:
break # this only breaks the inner while loop
isMPressed = True if button3_pressed() else False
isMPressed = True if button3_pressed() else False