docs: def set_servo_speed(self, goalspeed, led):
          """ Set the Herkulex in continuous rotation mode
  
          Args:
  
              goalspeed (int): the speed , range -1023 to 1023
              led (int): the LED color
                         0x00 LED off
                         0x04 GREEN
                         0x08 BLUE
                         0x10 RED
  
          """
          if goalspeed>0 :
              goalspeed_msb = (int(goalspeed)& 0xFF00) >> 8
              goalspeed_lsb = int(goalspeed) & 0xff
          elif goalspeed<0 :
              goalspeed_msb = 64+(255- ((int(goalspeed)& 0xFF00) >> 8))
              goalspeed_lsb = (abs(goalspeed) & 0xff)
  
          #print goalspeed_msb,goalspeed_lsb
          data = []
          data.append(0x0C)
          data.append(self.servoid)
          data.append(I_JOG_REQ)
          data.append(goalspeed_lsb)
          data.append(goalspeed_msb)
          data.append(0x02|led)
          data.append(self.servoid)
          data.append(0x00)
          send_data(data)