code: def pulse(self, fade_in_time=1, fade_out_time=1, n=None, background=True):
          
          on_time = off_time = 0
          self.blink(
              on_time, off_time, fade_in_time, fade_out_time, n, background)
docs: Make all LEDs fade in and out repeatedly. Note that this method will
          only work if the *pwm* parameter was :data:`True` at construction time.
  
          :param float fade_in_time:
              Number of seconds to spend fading in. Defaults to 1.
  
          :param float fade_out_time:
              Number of seconds to spend fading out. Defaults to 1.
  
          :type n: int or None
          :param n:
              Number of times to blink; :data:`None` (the default) means forever.
  
          :param bool background:
              If :data:`True` (the default), start a background thread to
              continue blinking and return immediately. If :data:`False`, only
              return when the blink is finished (warning: the default value of
              *n* will result in this method never returning).