Key Takeaways* Walmart may open "dark format" stores in urban areas as a way to fulfill e-commerce orders closer to high-income customers, CFO John David Rainey said.* Meanwhile, one of the company's best- selling Black Friday items was Apple AirPods.The wealthy have migrated to Walmart. Now the retailer wants to reciprocate.Walmart (WMT) would like to build a presence in urban areas that's closer to parts of the well-off population that h ...