Corporate aircraft and WN's 737s have the feature. The lights in the leading edge of the wing roots alternately flash.

I believe this feature was intended to be an 'anti-bird' item.....an attention-getter for birds if you will, that would cause them to ske-daddle out of the way.

Don't know that to be a fact, but was told that about seven years ago when I first saw it on the WN aircraft landing at MDW.

DRW