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)

Barny, the Harveys Brewery dog has a sniff of a pint of beer at the Great British Beer Festival, at Olympia in London, Tuesday, August 11, 2015. The five day event is organised by the Campaign for Real Ale (CAMRA), with over 900 real ales, ciders, perries and international beers on offer. (Photo by Kirsty Wigglesworth/AP Photo)

A student from “the cliff village” in Atule'er climbs newly-constructed steel ladders after school to go home for holidays, in Liangshan Sichuan province, China, November 19, 2016. The steel ladders which replaced the unsafe vine ladders shortened the time taken for the children to go home, from three hours to two. (Photo by Reuters/Stringer)

Salcomp players huddle at the center of the pitch of Arena da Amazonia after winning the Peladao amateur soccer tournament in Manaus, Brazil, Saturday, February 16, 2019. It is the team's second title, the first was in 2011. (Photo by Victor R. Caivano/AP Photo)

In this June 16, 2017 photo, Batel Delciner, 23, removes wood from a furnace to lower the heat cooking sugar juice at the Ti Jean distillery, which produces clairin, a sugar-based alcoholic drink, in Leogane, Haiti. The broth is cooked for about four hours after a fermentation period of four to eight days. (Photo by Dieu Nalio Chery/AP Photo)

Wu Lingling, a nurse from Central Hospital of Shanghai Fengxian District says goodbye to her husband Zhao Kun before leaving for Wuhan at Shanghai South Railway Station in east China's Shanghai, January 27, 2020. A team comprised of 50 medical workers from 40 hospitals in Shanghai left for Wuhan City on Monday to aid the novel coronavirus control efforts there. (Photo by Ding Ting/Xinhua News AgencyAlamy Live News)

A Chesterfield Borough Police telephone operator tests a gasmask with built in earpiece and microphone. The telephone service is considered one of the most important links in the coordination of ARP operations and must remain operational during air raids, 12th April 1939. (Photo by Fox Photos/Hulton Archive/Getty Images)

A changing of the honor guard ceremony by the Tomb of the Unknown Soldier in Alexander Garden by the Kremlin Wall in Moscow, Russia on May 29, 2020. (Photo by Vladimir Gerdo/TASS)