A dancer performs during Portuguese designer Teresa Martins for TM Collection during her runway show at the 41st edition of the Portugal Fashion Event in Lisbon, Portugal, 14 October 2017. (Photo by Jose Sena Goulao/EPA/EFE)

A spectator cools herself at a water spraying fan at the Australian Open tennis championships in Melbourne, Australia, Tuesday, January 17, 2017. (Photo by Kin Cheung/AP Photo)

Tour guides wearing traditional Chinese dress practice smiling by biting chopsticks at Qingming Grand-River Park in Kaifeng, central China's Henan Province on March 2, 2017, aiming to provide better service for visitors. (Photo by IPA Asia via ZUMA Wire)

Girls rest on stairs at the China Digital Entertainment Expo and Conference (ChinaJoy) in Shanghai, China July 27, 2017. (Photo by Aly Song/Reuters)

A horse-drawn cart passing through a section cut out of the base of a giant sequoia tree in the Mariposa groves of Yosemite Park, California. (Photo by Carleton E Watkins/Getty Images). 1870

Members of the “Avalon” team wearing 14th century knight costumes fight against each other on the bank of the Yenisei River during the regional amateurs tournament of clubs of historical reconstruction, “The Battle of the Nations 2015. Siberia”, in Krasnoyarsk January 24, 2015. (Photo by Ilya Naymushin/Reuters)

Members of the Indian Border Security Force (BSF) demonstrate their skills on motor-bikes during the BSF Golden Jubilee Day celebration in New Delhi on December 1, 2015. (Photo by Money Sharma/AFP Photo)