In this photo taken on Monday, January 5, 2015, a mallard duck attempts to walk on a frozen pond in Yukon, Okla. (Photo by Steve Gooch/AP Photo/The Oklahoman)

American Yoga teacher Dashama poses on a Yoga-board during a preview of the 46th International Boat Fair in Duesseldorf January 16, 2015. The BOOT 2015 watersports fair, with more than 1,600 international exhibitors will run in Duesseldorf from January 17 to January 25. (Photo by Ina Fassbender/Reuters)

In this April 20, 2017 photo, a woman is aided by fellow demonstrators after falling, overcome by tear gas, during anti-government protests in Caracas, Venezuela. Tens of thousands of protesters asking for the resignation of President Nicolas Maduro flooded the streets again, one day after three people were killed and hundreds arrested in the biggest anti-government demonstrations in years. (Photo by Ariana Cubillos/AP Photo)

A reveler, dressed as a Brazilian national army soldier holding a mock weapon with flowers jutting out of it, participates in the annual Gay Pride Parade in Sao Paulo, Brazil, Sunday, June 18, 2017. (Photo by Nelson Antoine/AP Photo)

A military instructor helps a boy to shoot a rifle with blanks at a weapon exhibition during a military show in St.Petersburg, Russia, Sunday, January 17, 2016. (Photo by Dmitry Lovetsky/AP Photo)

An American flag is visible in the windows of the cupola aboard the International Space Station. Thanks to a bill passed by Texas legislators in 1997 that put in place technical voting procedure for astronauts – nearly all of whom live in Texas – they have the ability to vote from space through specially designed absentee ballots. To preserve the integrity of the secret vote, the ballot is encrypted and only accessible by the astronaut and the county clerk responsible for casting the ballot. (Photo by NASA)

People walk past a New Year fir tree made of toys at a park in Krasnoyarsk, Siberia, Russia January 2, 2017. (Photo by Ilya Naymushin/Reuters)

A British policewoman chasing after a group of naked street boys by the Serpentine in Hyde Park, London. (Photo by Reg Speller/Getty Images). 1926