How to programmatically dim Mac backlit keyboard

Is there a way to programmatically dim a backlit keyboard 开发者_StackOverflowon a Mac?

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UInt64 lightInsideGetLEDBrightness()
{
kern_return_t kr = 0;
IOItemCount   scalarInputCount  = 1;
IOItemCount   scalarOutputCount = 1;
UInt64        in_unknown = 0, out_brightness;
//kr = IOConnectMethodScalarIScalarO(dataPort, kGetLEDBrightnessID,
//                                  scalarInputCount, scalarOutputCount, in_unknown, &out_brightness);
kr = IOConnectCallScalarMethod(dataPort, kGetLEDBrightnessID, &in_unknown, scalarInputCount, &out_brightness, &scalarOutputCount);
return out_brightness;
}

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