A man looks inside an overturned truck after an accident along the road between Nouahibou and Nouakchott, Mauritania December 3, 2009. (Photo by Rafael Marchante/Reuters)

In this Sunday, April 6, 2014 photo, Valery Palma prepares to blow out the candle on a birthday cake for her one-year-old dachshund Camila, at Camila's birthday party in Mexico City. Palma, who has two dogs, spent $300 on the birthday party for 11 canines and 16 people, complete with cake, presents and snacks, at a dog hotel featuring a gym and massage and aromatherapy services. (Photo by Rebecca Blackwell/AP Photo)

A couple chats at a park during sunset in Chihuahua November 15, 2014. (Photo by Jose Luis Gonzalez/Reuters)

In this Friday, March 13, 2015, Mitch Seavey's lead dogs with frosty whiskers at the Huslia, Alaska, checkpoint for the Iditarod Trail Sled Dog Race. (Photo by Loren Holmes/AP Photo/Alaska Dispatch News)

Cheng Chen (R), a 27-year-old worker at a state-owned enterprise, poses for a photograph with his nephew who is wearing his home-made Iron Man armour, in Xuzhou, Jiangsu province April 13, 2015. It cost Cheng about 500 yuan ($81 USD) to make the armour, which weighs about 4 kilograms, with plastic boards and LED lights, local media reported. (Photo by Reuters/Stringer)

People take part in a Halloween street party at Lan Kwai Fong on October 31, 2016 in Hong Kong. Halloween, a contraction of All Hallows' Evening, falls on the day before All Saints' Day on November 1, a holiday when Christians remember their deceased loved ones. (Photo by Lam Yik Fei/Getty Images)

In this picture taken on November 28, 2016, a hot-air balloon carrying tourists sails over the archeological site at sunrise in Bagan. Located in central Myanmar, Bagan is home to more than 2,000 ancient Buddhist monuments deeply revered in the Buddhist-majority nation and is one of the country's most popular tourist destinations. (Photo by Dale De La Rey/AFP Photo)

Public Space series, 2015. This series by Morteza Niknahad and Behnam Zakeri tends toward cinema, taking an almost cartoonish view of modern life in Iran. This work was inspired by the social life of dolphins. (Photo by Morteza Niknahad and Behnam Zakeri/The Guardian)