An Omani woman prepares for a traditional dance during a ceremony attended by Britain's Prince Charles and his wife, Camilla, Duchess of Cornwall in Muscat, Oman, Saturday, November 5, 2016. The royal couple have started a three-nation royal tour of the Gulf in Oman. (Photo by Kamran Jebreili/AP Photo)

A member of a local swimming club holds a Russian national flag as he dives in at the start of a 24-hour swimming marathon near the western Siberian city of Barnaul March 29, 2014. Thirty members of the club will swim in turn during the event, held to mark Crimea becoming part of Russia, local media reported. (Photo by Andrei Kasprishin/Reuters)

Sebastien Bourdais, of Colombia, makes a corner during practice for the IndyCar auto race Saturday, June 13, 2015, in Toronto. (Nathan Denette/The Canadian Press via AP)

Aluminium ingots are stored at a foundry shop of the Rusal Khakassia aluminium smelter outside the town of Sayanogorsk, Russia, September 3, 2015. Russia's Rusal has decided to delay a decision on its possible first dividend since listing five years ago though its second-quarter core profit more than doubled thanks to cost cuts and a weaker rouble. (Photo by Ilya Naymushin/Reuters)

A man walks on the road between Nouahibou and Nouakchott, where three Spanish aid workers were abducted in Mauritania, December 3, 2009. (Photo by Rafael Marchante/Reuters)

Sichuan Opera performer Wu Yonghong, 26 years, of the Jinyuan Opera Company performs for villagers at the Dongyue Temple on May 2, 2016 in Cangshan, Sichuan province, China. Sichuan opera is a vibrant, centuries-old tradition that showcases the joys and challenges of daily life in rural China with tales of love, tradition, and family honor. Photo by Kevin Frayer/Getty Images)

The driver of a Maerlitram (fairy tram), dressed as a Santa Claus, walks past a car which crashed into the tram in Zurich, Switzerland December 7, 2017. (Photo by Angelika Gruber/Reuters)

A man from the Ogiek community harvests honey in Mount Elgon game reserve, where they have reached an agreement with the government allowing them to remain in their ancestral lands in western Kenya, April 26, 2016. (Photo by Katy Migiro/Reuters)