Start over and get a track.

def begin(self):
        '''
        Start over and get a track.
        '''
        # Check for a start metasong
        if self.start:
            # We are in the beginning song
            self.at_beginning = True
            # And on the first track.
            self.pos = 0
        else:
            # We aren't in the beginning song
            self.at_beginning = False
            # So we need to get new one.
            self._new_song()
        return self._get_song()