code: def set_servo_pulsewidth(self, user_gpio, pulsewidth):
          
          res = yield from self._pigpio_aio_command(_PI_CMD_SERVO, user_gpio, int(pulsewidth))
          return _u2i(res)
docs: Starts (500-2500) or stops (0) servo pulses on the GPIO.
           user_gpio:= 0-31.
          pulsewidth:= 0 (off),
                       500 (most anti-clockwise) - 2500 (most clockwise).
          The selected pulsewidth will continue to be transmitted until
          changed by a subsequent call to set_servo_pulsewidth.
          The pulsewidths supported by servos varies and should probably
          be determined by experiment. A value of 1500 should always be
          safe and represents the mid-point of rotation.
          You can DAMAGE a servo if you command it to move beyond its
          limits.
          ...
          yield from pi.set_servo_pulsewidth(17, 0)    # off
          yield from pi.set_servo_pulsewidth(17, 1000) # safe anti-clockwise
          yield from pi.set_servo_pulsewidth(17, 1500) # centre
          yield from pi.set_servo_pulsewidth(17, 2000) # safe clockwise
          ...