code: func (w *Window) JoystickAxis(js Joystick, axis int) float64 {
  	return w.currJoy.getAxis(js, axis)
  }
docs: // JoystickAxis returns the value of a joystick axis at the last call to Window.Update.
  // If the axis index is out of range, this will return 0.
  //
  // This API is experimental.