def play_tone(self, pitch, duration):
    pitch, duration = float(pitch), float(duration)

    if pitch == 0:
        time.sleep(duration)
        return

    p = GPIO.PWM(self.pin, pitch)
    p.start(0.5)
    time.sleep(duration)
    p.stop()

def play(self, tune):
    for pitch, duration in tune:
        self.play_tone(pitch, duration)

(gdb) bt
#0  0x764dac54 in output_gpio () from /usr/lib/python3/dist-packages/RPi/_GPIO.cpython-35m-arm-linux-gnueabihf.so
#1  0x764dc9bc in pwm_thread () from /usr/lib/python3/dist-packages/RPi/_GPIO.cpython-35m-arm-linux-gnueabihf.so
#2  0x00001000 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb)