Masked Palestinian demonstrators hide behind a metal plate during clashes with Israeli soldiers on March 12, 2018 in the West Bank town of Birzeit, near Ramallah, following a protest by students of the Birzeit University against the arrest of the the head of Palestinian student council by an Israeli undercover commando. (Photo by Abbas Momani/AFP Photo)

Julian, left, is photographed by his mother with friend Gianluca, right, under water at a public pool in Gelsenkirchen, Germany, on a hot Friday, July 3, 2015. Germany faces a heat wave with temperatures up to 38 degrees Celsius (100 degrees Fahrenheit) at the weekend. (Photo by Martin Meissner/AP Photo)

A team from Woody's Ice Cream shop wrangle a large inflatable dinosaur down the street during the Independence Day Parade in Fairfax, Virginia July 4, 2015. Americans marched in star-spangled parades, ran relay races, gathered for fireworks shows and crowned a new world hot dog eating champion as they celebrated Independence Day in traditional style on Saturday. (Photo by Jonathan Ernst/Reuters)

Russia-backed separatists stand at the site of the crashed Malaysia Airlines Flight 17 plane, near the village of Hrabove, eastern Ukraine, Thursday, July 16, 2015. The fighters said they have arrived to protect the media and make sure the MH17 crash site is clear of ammunition and mines. A year since a Malaysia Airlines Boeing 777 was blown out of the sky over war-ravaged eastern Ukraine, killing 298 people, there has been little official word of progress in determining what brought down Flight MH17. (Photo by Antoine E. R. Delaunay/AP Photo)

Cuban girls dressed as nurses and a lizard wait for their turn to dance during a visit by the Gay Men's Chorus of Washington in Havana July 13, 2015. The choir made its first appearance on July 12, 2015 in Cuba as part of a tour that will include a dozen concerts in the context of the restoration of relations between the island and the United States. (Photo by Enrique de la Osa/Reuters)

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)

A group of men play Myanmar's traditional sport of chinlone in Naypyitaw, Myanmar, Friday, November 18, 2016. (Photo by Aung Shine Oo/AP Photo)