code: def playTone(self, freq, reps = 1, delay = 0.1, muteDelay = 0.0):
          
          if freq == 0: 
              self.stopTone()
              self._delay(delay)
              #sleep(delay)
              return False
  
          if self._pwmPlayer == None: self._initPWMPlayer(freq)
  
          for r in range(0,reps):
              self._pwmPlayer.start(self.TONE_DUTY)
              self._pwmPlayer.ChangeFrequency( freq )
              self._delay(delay)
              #sleep(delay)
  
              if muteDelay>0:
                  self.stopTone()
                  self._delay(muteDelay)
                  #sleep(muteDelay)
  
          return True
docs: !
          \~english Play a tone
          \~chinese 播放音符
          \~english 
          @param freq
          @param reps
          @param delay >= 0(s) if 0 means do not delay. tone play will be Stop immediately <br>
          @param muteDelay >= 0(s) If 0 means no pause after playing, play the next note immediately
          \~chinese 
          @param freq: 频率
          @param reps: 重复次数
          @param delay >= 0(s) 如果是 0 意味着不延迟。 音符会立即停止播放 <br>
          @param muteDelay >= 0(s) 如果是 0 表示音符播放结束后没有停顿，立刻播放下一个音符