def previous_waveform(self): index = WAVEFORMS.index(self._wave) if index - 1 < 0: self.waveform = WAVEFORMS[-1] else: self.waveform = WAVEFORMS[index-1]
def next_waveform(self): index = WAVEFORMS.index(self._wave) if index + 1 > len(WAVEFORMS) - 1: self.waveform = WAVEFORMS[0] else: self.waveform = WAVEFORMS[index+1]