A Southwest Airlines jet takes off from Reagan National Airport with a thunderhead to the east on June 20, 2017 in Alexandria, VA. (Photo by Jonathan Newton/The Washington Post)

An Egyptian passenger sits on the locomotive of a train as it leaves Cairo train station in Egypt, Wednesday, October 14, 2015. (Photo by Amr Nabil/AP Photo)

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)

Green Bay Packers' Johnathan Calvin rides a bike to NFL football training camp on July 27, 2017, in Green Bay, Wis. (Photo by Morry Gash/AP Photo)

An Iraqi soldier plays with an accordion found on the street while on patrol in the western neighborhood of Tamuz in Mosul on May 23, 2017, after the area was retaken during the ongoing offensive against Islamic State (IS) group fighters. (Photo by Ahmad Al-Rubaye/AFP Photo)

A workman walks past a large mural on the side of a building during the “Sand Sea & Spray” Urban Art Festival in Blackpool, north west England on July 11, 2015. (Photo by Oli Scarff/AFP Photo)

A woman waters the plants outside her house in an alley at a slum in Mumbai October 28, 2014. (Photo by Danish Siddiqui/Reuters)

Lady Gaga performs at Staples Center on August 11, 2010 in Los Angeles, California. (Photo by Jason Merritt/Getty Images)