code: func (g *Driver) SetMotorPower(motor Motor, power int8) error {
  	return g.writeBytes([]byte{
  		goPiGo3Address,
  		SET_MOTOR_PWM,
  		byte(motor),
  		byte(power),
  	})
  }
docs: // SetMotorPower sets a motor's power from -128 to 127.