Play a sound file (wav format) at a given volume.

        :param string wav_file: The sound file path
        :param int volume: The play volume, in percent of maximum volume

        :param play_type: The behavior of ``play_file`` once playback has been initiated
        :type play_type: ``Sound.PLAY_WAIT_FOR_COMPLETE``, ``Sound.PLAY_NO_WAIT_FOR_COMPLETE`` or ``Sound.PLAY_LOOP``

        :returns: When ``Sound.PLAY_NO_WAIT_FOR_COMPLETE`` is specified, returns the spawn subprocess from ``subprocess.Popen``; ``None`` otherwise

def play_file(self, wav_file, volume=100, play_type=PLAY_WAIT_FOR_COMPLETE):
        """ Play a sound file (wav format) at a given volume.

        :param string wav_file: The sound file path
        :param int volume: The play volume, in percent of maximum volume

        :param play_type: The behavior of ``play_file`` once playback has been initiated
        :type play_type: ``Sound.PLAY_WAIT_FOR_COMPLETE``, ``Sound.PLAY_NO_WAIT_FOR_COMPLETE`` or ``Sound.PLAY_LOOP``

        :returns: When ``Sound.PLAY_NO_WAIT_FOR_COMPLETE`` is specified, returns the spawn subprocess from ``subprocess.Popen``; ``None`` otherwise
        """
        if not 0 < volume <= 100:
            raise ValueError('invalid volume (%s)' % volume)

        if not wav_file.endswith(".wav"):
            raise ValueError('invalid sound file (%s), only .wav files are supported' % wav_file)

        if not os.path.isfile(wav_file):
            raise ValueError("%s does not exist" % wav_file)

        self.set_volume(volume)
        self._validate_play_type(play_type)

        with open(os.devnull, 'w') as n:

            if play_type == Sound.PLAY_WAIT_FOR_COMPLETE:
                pid = Popen(shlex.split('/usr/bin/aplay -q "%s"' % wav_file), stdout=n)
                pid.wait()

            # Do not wait, run in the background
            elif play_type == Sound.PLAY_NO_WAIT_FOR_COMPLETE:
                return Popen(shlex.split('/usr/bin/aplay -q "%s"' % wav_file), stdout=n)

            elif play_type == Sound.PLAY_LOOP:
                while True:
                    pid = Popen(shlex.split('/usr/bin/aplay -q "%s"' % wav_file), stdout=n)
                    pid.wait()