An injured boy who is undergoing surgery, after he was injured in what activists said was an airstrike by forces loyal to Syria's president Bashar al-Assad, rests inside a field hospital in the Douma neighborhood of Damascus, Syria December 5, 2015. Douma in Syria, an area controlled by rebels fighting to topple President Bashar al-Assad, has been shelled continuously for the past three years. The injured are taken to basements and shelters transformed into field hospitals run by medical staff who have stayed in the battered neighbourhood of Damascus. (Photo by Bassam Khabieh/Reuters)

Models painted in camouflage colours to blend in with the background pose for Chinese artist Liu Bolin's artwork “Dongji”, or Winter Solstice, on the second day after China's capital Beijing issued its second ever “red alert” for air pollution, in Beijing, China, December 20, 2015. In this artwork, Liu wants to express his concerns about China and its people, including air pollution problem, Liu told Reuters. (Photo by Kim Kyung-Hoon/Reuters)

Ultra Orthodox Jews look at the body of an alleged Palestinian assailant in Jerusalem Saturday, December 26, 2015. According to a police spokeswoman, policemen approached a man who drew their suspicions just outside the Old City for following a pair of Jewish worshippers. Then he pulled out a knife and tried to stab one of them, officers opened fire and killed the assailant. (Photo by Mahmoud Illean/AP Photo)

Soldier boys at Fort Dix, N.J., learn something about guns during their working hours, as they show their girlfriends at a camp dance, December 13, 1940. In front row, playing with the coin amusement gun, from left: Pvt. Tom D'Amato of West Orange; Rose Sinkewicz, behind gun site, of Trenton; Julia Ivans of Trenton, and Pvt. Vernon Landers of Kearney. Back row: Pvts. William Sargent and William Corlies of Philadelphia. (Photo by AP Photo)

A physically disabled fox walks with its walking wheels wheelchair, developed by an animal lover by Van Yuzuncu Yil University Wildlife Conservation and Rehabilitation Center, after the fox found wounded in the urban countryside in Van, Turkey on December 05, 2020. The fox also received a physical treatment at the center. (Photo by Ozkan Bilgin/Anadolu Agency via Getty Images)

Anthony Joshua punches Kubrat Pulev during the IBF, WBA, WBO and IBO World Heayweight Title fight between Anthony Joshua and Kubrat Pulev at The SSE Arena, Wembley on December 12, 2020 in London, England. A limited number of fans (1000) are welcomed back to sporting venues to watch elite sport across England. This was following easing of restrictions on spectators in tiers one and two areas only. (Photo by Andrew Couldridge – Pool/Getty Images)

Young women wearing facemasks and traditional costumes of Song dynasty and Tang dynasty are seated on a bench in a park next to the East Lake in Wuhan, in China’s central Hubei province on May 17, 2020. The Guardian picture desk has chosen on December 17, 2020, the AFP photojournalist Hector Retamal as “Agency Photographer of the Year 2020” for his coverage of the novel coronavirus Covid-19 pandemic in Wuhan, China. (Photo by Hector Retamal/AFP Photo)

WrestlerTeddy Sheedi (L) fights his opponent during the traditional Sindhi Malakhra wrestling in Karachi, Pakistan, 13 December 2020. A Malakhra match begins with both wrestlers tying a twisted cloth around the opponent's waist. Each one then holds onto the opponent's waistcloth and tries to throw him to the ground. (Photo by Shahzaib Akber/EPA/EFE)