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Employees march of the line towards the assembly area after row call at a Pegatron Corp. factory in Shanghai, China, on Friday, April 15, 2016. This is the realm in which the world's most profitable smartphones are made, part of Apple Inc.'s closely guarded supply chain. (photo by Qilai Shen/In Pictures via Getty Images Images)

Employees march of the line towards the assembly area after row call at a Pegatron Corp. factory in Shanghai, China, on Friday, April 15, 2016. This is the realm in which the world's most profitable smartphones are made, part of Apple Inc.'s closely guarded supply chain. (photo by Qilai Shen/In Pictures via Getty Images Images)