Couples take part in a competition during a mass wedding of 64 doctoral student couples at Harbin Institute of Technology, a university in Harbin, Heilongjiang province, China, June 4, 2017. (Photo by Reuters/Stringer)

A commuter exits a closed off station after a subway train derailment, Tuesday, June 27, 2017, in the Harlem neighborhood of New York. A subway train derailed near a station in Harlem on Tuesday, frightening passengers and resulting in a power outage as people were evacuated from trains along the subway line. The Fire Department of New York said a handful of people were treated for minor injuries at around 10 a.m. It said there was smoke but no fire. Delays were reported throughout the subway system. (Photo by Mary Altaffer/AP Photo)

In this December 29, 2004 file photo, Kusol Wetchakul offers prayers for the soul of his sister, at dawn along the beach near Khao Lak, Thailand. Wetchakul's sister was swept out to sea and believed drowned as she sold goods to tourists on the popular tourist beach just north of Phuket. Friday marks the 10th anniversary of one of the deadliest natural disasters in world history: a tsunami, triggered by a massive earthquake off the Indonesian coast, leaving more than 230,000 people dead in 14 countries and causing about $10 billion in damage. (Photo by David Longstreath/AP Photo)

A Sadhu or a Hindu holy man offers prayers while sitting inside a circle of burning “Upale” (or dried cow dung cakes) on the occasion to mark the Basant or spring festival, on the banks of river Ganga in the northern Indian city of Allahabad January 24, 2015. Basant is celebrated mainly in the northern Indian states marking the start of the spring season. (Photo by Jitendra Prakash/Reuters)

An Egyptian passenger sits on the locomotive of a train as it leaves Cairo train station in Egypt, Wednesday, October 14, 2015. (Photo by Amr Nabil/AP Photo)

A man steers with his legs while riding a motorcycle on a road in Vietnam's northern Hoa Binh province, outside Hanoi, October 15, 2015. (Photo by Reuters/Kham)

A petitioner with her grievances written on her clothes walks along a street in Beijing Tuesday, December 22, 2015. After months behind bars, Pu Zhiqiang, one of China's most prominent human rights lawyers, left a detention center Tuesday after receiving a suspended prison sentence in a case involving online comments critical of the ruling Communist Party. (Photo by Ng Han Guan/AP Photo)

A conductor (C) collects fares from candy floss sellers as they travel in a tram to a marketplace early morning in Kolkata, India, December 23, 2015. (Photo by Rupak De Chowdhuri/Reuters)