A machine works on a Rio 2016 Olympic medal at the Casa da Moeda do Brasil (Brazilian Mint) in Rio de Janeiro, Brazil, June 28, 2016. The Casa da Moeda do Brasil is the Brazilian mint, owned by the Brazilian government and administratively subordinated to the Ministry of Finances. It was established in 1694. (Photo by Sergio Moraes/Reuters)

A string is used to ensure that the skirts of female members of the honour guard are in the same height from the ground as they prepare for a welcoming ceremony for Congo Republic President Denis Sassou Nguesso outside the Great Hall of the People in Beijing, China, July 5, 2016. (Photo by Jason Lee/Reuters)

2016 Rio Olympics, Handball, Preliminary, Women's Preliminary Group B Netherlands vs France, Future Arena, Rio de Janeiro, Brazil on August 6, 2016. Lois Abbingh (NED) of Netherlands celebrates a goal. (Photo by Marko Djurica/Reuters)

File photo taken on July 24, 2011 shows the scenery of karst landform in Dacai Township under Maonan Autonomous County of Huaijiang, south China's Guangxi Zhuang Autonomous Region. The World Heritage Committee on Monday inscribed an extension of South China Karst, a natural World Heritage Site since 2007, into the UNESCO's World Heritage List. (Photo by Wang Xiufa/Xinhua)

This picture taken on September 9, 2014 shows a waiteress handing over food to customers at a prison themed restaurant in Tianjin. As more themed restaurants are popular in China, a “prison style” restaurent in Tianjin is aimed at reminding people to observe the law and to be good citizens. (Photo by Wang Zhao/AFP Photo)

Rihanna and Drake perform at the BRIT Awards at the O2 arena in London, Britain, February 24, 2016. (Photo by Stefan Wermuth/Reuters)

Soldiers from Japan's Ground Self Defense Force come ashore in amphibious assault vehicle as they train alongside U.S. Marines during the bilateral annual Iron Fist military training exercise in Camp Pendleton, California February 26, 2016. (Photo by Mike Blake/Reuters)

People watch a total solar eclipse from the Bay Bridge in Palu, Central Sulawesi, Indonesia March 9, 2016 in this photo taken by Antara Foto. The rare astronomical event is being witnessed Wednesday along a narrow path that stretches across 12 provinces encompassing three times zones and about 40 million people. (Photo by Mohamad Hamzah/Reuters/Antara Foto)