>>> last = False
>>>
>>> while True:
...         current = GPIO.input(3)
...         if ( current != last ):
...                 last = current
...                 print(current)
...         time.sleep(0.01);
...
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True
False
True