In this Wednesday, June 8, 2016 photo, Joe Giles, an actor portraying a zombie in “The Walking Dead”, poses with social media reporter Danielle Datu during a walker boot camp at Universal Studios Hollywood in Los Angeles. (Photo by Jae C. Hong/AP Photo)

Couples take part in the “Love and Challenge Marathon” in Hanoi, Vietnam, 16 August 2015. Fifty couples, who are going to get married, participated in the event which is held the fifth time. This year, the winners of the marathon received a honeymoon trip to Malaysia. (Photo by Luong Thai Linh/EPA)

Robert Price of TREWGrip LLC demonstrates a TREWGrip handheld rear-type keyboard and air mouse for Apple and Android tablets at the “CES: Unveiled”, media preview for International CES, at the Mandalay Bay Convention Center in Las Vegas on January 5, 2014. (Photo by Robyn Beck/AFP Photo)

This artist's scoreboard displays a fictional game between Mars and Earth, with Mars in the lead. It refers to the success rate of sending missions to Mars, both as orbiters and landers. Of the previous 39 missions targeted for Mars from around the world, 15 have been successes and 24 failures. For baseball fans, that's a batting average of .385. The United States has had 13 successes out of 18 attempts, or a “batting average” of .722. NASA's Curiosity rover, set to land on the Red Planet the evening of Aug. 5, 2012 PDT (morning of Aug. 6 EDT), will mark the United States' 19th attempt to tackle the challenge of Mars, and the world's 40th attempt. (Image by NASA/JPL-Caltech)

Dynam employees say a greeting message as they receive customer-care training ahead of the grand opening of the company's pachinko parlour in Fukaya, north of Tokyo July 29, 2014. Japan's once-booming pachinko industry, grappling with a greying customer base and the threat of new competition from casinos, is adopting a softer touch and smoke-free zones to lure a new generation of players, particularly women. Pachinko, a modified version of pinball, is a fading national obsession, with about 12,000 parlours nation-wide and one in thirteen people playing the game. But that figure is declining as the population shrinks and younger people prefer games on their mobile phones. (Photo by Issei Kato/Reuters)

An opposition fighter from the Failaq al-Rahman brigade fires a heavy machine gun in Jobar, a rebel-held district on the eastern outskirts of the Syrian capital Damascus, on March 19, 2017. (Photo by Amer Almohibany/AFP Photo)

A woman carries earthen pots to fill them with drinking water on a hot summer day, on the outskirts of Ajmer, Rajasthan, India April 25, 2017. (Photo by Himanshu Sharma/Reuters)

People enjoy the beach as they look at a forest fire in La Croix-Valmer, near Saint-Tropez, on July 25, 2017. Firefighters battle blazes that have consumed swathes of land in southeastern France for a second day, with one inferno out of control near the chic resort of Saint-Tropez, emergency services say. (Photo by Valery Hache/AFP Photo)