def _get_preview_alpha(self):
    self._check_camera_open()
    warnings.warn(PiCameraDeprecated('PiCamera.preview_alpha is deprecated; use PiCamera.preview.alpha instead'))
    if self.preview:
        return self.preview.alpha
    else:
        return self._preview_alpha
def _get_preview_alpha(self):
    self._check_camera_open()
    warnings.warn(PiCameraDeprecated('PiCamera.preview_alpha is deprecated; use PiCamera.preview.alpha instead'))
    if self.preview:
        return self.preview.alpha
    else:
        return self._preview_alpha