Firefighters watch as an air tanker drops retardant while battling the Ferguson fire in the Stanislaus National Forest, near Yosemite National Park, California on July 21, 2018. A fire that claimed the life of one firefighter and injured two others near California's Yosemite national park has almost doubled in size in three days, authorities said Friday. (Photo by Noah Berger/AFP Photo)

Revellers enjoy themselves during Hogmanay celebrations in Edinburgh, Scotland on December 31, 2017. (Photo by Russell Cheyne/Reuters)

Two white storks stand close to each other on their nest on a tree in Zerbolo, Italy, Thursday, October 26, 2017. (Photo by Antonio Calanni/AP Photo)

People walk past part of an outdoor display as preparations continue for the upcoming pop culture convention Comic Con in San Diego, California, U.S., July 17, 2018. (Photo by Mike Blake/Reuters)

Katie Rose Hobbs and Kirsten Elizabeth Pobjoy of British Aerosuperbatics Wingwalking Team perform ballet in the air during Huangguoshu Waterfalls Flight Conference on August 3, 2018 in Anshun, Guizhou Province of China. Huangguoshu Waterfalls Flight Conference including 18 aircraft from seven aerobatic teams from all over the world kicked off on Friday. (Photo by VCG via Getty Images)

Women are reflected in a puddle as they walk across Red Square in Moscow, Russia on April 26, 2018. (Photo by Yuri Kadobnov/AFP Photo)

Commuters hang off a local passenger train in the morning in Colombo, Sri Lanka September 8, 2016. (Photo by Dinuka Liyanawatte/Reuters)

People look at a man, who residents said was killed by al Qaeda militants, hanging on a bridge in Yemen's southeastern city of Mukalla June 17, 2015. Al Qaeda militants in Yemen killed two alleged Saudi spies, residents said, accusing them of planting tracking devices which enabled the assassination of the group's leader in a suspected U.S. drone strike. (Photo by Reuters/Stringer)