A dejected German Grenadier carrying a machine gun on his shoulder in front of a building on fire during the German retreat in Russia. (Photo by Keystone/Getty Images). 1944

In this January 25, 2013 photo, snake handler Saintilus Resilus holds a snake in front of his lips as he trains the snake to recognize his smell as he prepares for his street performances during the pre-Lenten Carnival season, at his home in Petionville, Haiti. Resilus sees himself as something of a performance artist, showing off with snakes and other animals that Haitians don't see every day, earning tips from impromptu audiences. (Photo by Dieu Nalio Chery/AP Photo via Matt Dayhoff)

Lightning from a tornadic thunderstorm passing over Clearwater, Kansas strikes at an open field May 19, 2013. A massive storm front swept north through the central United States on Sunday, hammering the region with fist-sized hail, blinding rain and tornadoes, including a half-mile wide twister that struck near Oklahoma City. News reports said at least one person had died. (Photo by Gene Blevins/Reuters)

Soldiers stand in front of a floral decoration during celebrations to commemorate the 70th anniversary of the establishment of the Vietnam People's Army at the National Convention Center in Hanoi December 20, 2014. The Vietnam People's Army was founded on December 22, 1944 and led by General Vo Nguyen Giap in Cao Bang province, initially with only 34 members. (Photo by Reuters/Kham)

Senator Barack Obama (D-IL) (R) stands in front of Senator Hillary Clinton (D-NY) as they arrive for U.S. President George W. Bush's annual State of the Union speech to a joint session of Congress at the U.S. Capitol in Washington in this January 23, 2007 file photo. Hillary Clinton announced her second run for the presidency on April 12, 2015 starting her campaign as the Democrats' best hope of fending off a crowded field of lesser-known Republican rivals and retaining the White House. (Photo by Larry Downing/Reuters)

Mongolia's Olympic wrestler Battsetseg Soronzonbold (front) fights with her training partner during a daily training session at the Mongolia Women’s National Wrestling Team training centre in Bayanzurkh district of Ulaanbaatar, Mongolia, July 1, 2016. Battsetseg Soronzonbold became a national hero in her native Mongolia after winning wrestling bronze at the London Olympics and is determined to turn the medal into gold in Rio next month. (Photo by Jason Lee/Reuters)

Wild foxes walk in front of a launch pad prior the launch of the Soyuz-FG rocket booster with Soyuz MS space ship carrying a new crew to the International Space Station, ISS at the Russian leased Baikonur cosmodrome, Kazakhstan, Thursday, July 7, 2016. The Russian rocket carries U.S. astronaut Kate Rubins, Russian cosmonaut Anatoly Ivanishin, and Japan astronaut Takuya Onishi. (Photo by Dmitri Lovetsky/AP Photo)

Mercedes driver Nico Rosberg, right, of Germany steers his car in front of Mercedes driver Mercedes driver Lewis Hamilton of Britain, center and Ferrari driver Sebastian Vettel of Germany during the Austrian Formula One Grand Prix race at the Red Bull Ring in Spielberg, southern Austria, Sunday, June 21, 2015. (AP Photo/Kerstin Joensson)