A woman uses a tree branch to fight a fire on the road leading to the village of Parada, near Mortagua, northern Portugal, Thursday, August 11 2016. Firefighters in Portugal are battling multiple blazes fed by brush in a hot, dry summer for a sixth straight day. Major fires have also been raging in northwestern Spain and southern France. (Photo by Sergio Azenha/AP Photo)

The Breitling DC-3, HB-IRJ, plane fly escorted by Italian Air Force's aerobatic demonstration team, the Frecce Tricolori, during the last stage of its world tour two days ahead of the International Sion Air Show, in Sion, Switzerland, 13 September 2017. From March to September 2017, the Breitling DC-3 from 1940 has done a grand world tour in several stages, over 28 countries and flies 50000km, an amazing accomplishment for this legendary plane that will be celebrating its 77th birthday. (Photo by Christian Merz/EPA/EFE)

Two female revelers engage in a beer drinking contest in the Hacker Pschorr tent on the first day of the 2017 Oktoberfest beer fest on September 16, 2017 in Munich, Germany. Oktoberfest is the world's largest beer celebration and typically draws over six million visitors over its three-week run. Oktoberfest includes massive beer tents, each run by a different Bavarian brewer, as well as amusement rides and activities. (Photo by Philipp Guelland/Getty Images)

Eagle Prime (MK3), a giant robot by MegaBots Inc. which manufactures giant piloted humanoid fighting robots headquartered in Berkeley, California on October 18, 2017. (Photo by Courtesy Michael Mauldin/Reuters/MegaBots Inc)

Members of p*ssy Riot perform in concert during Day For Night festival on December 16, 2017 in Houston, Texas. (Photo by Gary Miller/Getty Images)

A US Marine leads two Viet Cong suspects in restraints during the Tet Offensive on February 20, 1967. (Photo by Bettmann Archive/Getty Images)

Members of Hashid Shaabi or Popular Mobilization Forces (PMF) fire towards Islamic State militant positions in west of Mosul, Iraq, December 28, 2016. (Photo by Reuters/Stringer)

Anti-pollution protesters wearing traditional costumes and contemporary gas masks ride bicycles in the Qingming Grand river park in Kaifeng, Henan Province, China on January 1, 2017. The Beijing Municipal Environmental Protection Bureau extended an “orange alert” for heavy air pollution for three more days. (Photo by SIPA Asia/Rex Features/Shutterstock)