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]
