Hospitality staff members laugh as they stand on Tiananmen Square before the closing ceremony of China's 19th Party Congress at the Great Hall of the People in Beijing, Tuesday, October 24, 2017. The ruling Communist Party on Tuesday formally lifted Xi Jinping's status to China's most powerful ruler in decades, setting the stage for the authoritarian leader to tighten his grip over the country while pursuing an increasingly muscular foreign policy and military expansion. (Photo by Mark Schiefelbein/AP Photo)

A flock of starlings is seen as they perform their traditional dance fly before landing to sleep during the sunset near the southern Arab Israeli city of Rahat, in the northern Israeli Negev desert, on February 2, 2015. (Photo by Menahem Kahana/AFP Photo)

Chinese artist Kong Ning poses in a costume symbolizing a butterfly, which is decorated with 365 masks on its wings to represent the number of days in a year, during her performance art at the Badaling section of the Great Wall on the outskirts of Beijing January 1, 2015. Kong, whose works include themes related to China's air pollution problem, named her new performance art “Hua Die” (transforming into a butterfly) and performed it on the first day of the new year as she hopes that China has clean air for this year. (Photo by Kim Kyung-Hoon/Reuters)

A view of the Sheikh Zayed highway in Dubai and some high rise buildings, November 8, 2007. (Photo by Steve Crisp/Reuters)

A model poses with “The Wellbeing Toilet” the winning entry from a Dyno-Rod Initiative to create a new design for the domestic toilet at Central Saint Martins on November 18, 2013 in London, England. The concept was commissioned to mark 50 years of Dyno-Rod and World Toilet Day on November 19th, 2013 The “Wellbeing Toilet” looks at the health and wellbeing aspect of getting rid of your bodily waste by being sculpted to enhance the position of your body by enabling you to squat rather than sit. (Photo by Miles Willis/Getty Images for Dyno-Rod)

In this January 27, 2014 photo, snow rollers dot a lot at the northwest corner of Olive and North Main streets in Akron, Ohio. The snow balls are formed naturally when high winds push snow across a hill. (Photo by Michael Chritton/AP Photo/Akron Beacon Journal)

A young girl navigates her way around Hampton Court maze in the spring sunshine on May 2, 2009 in London, England. The Hampton Court maze is one of the most famous hedge mazes in the world and was planted between 1689 and 1695 by George London and Henry Wise. (Photo by Dan Kitwood/Getty Images)

A huge atlas moth, with a wingspan of more than 9in, photographed on an areca nut plantation in Sirsi, India. (Photo by Uday Hegde/Close Up Photographer of the Year)