An Iraqi Muslim woman walks past Christmas decorations for sale in the Shiite holy city of Najaf on December 17, 2015. (Photo by Haidar Hamdani/AFP Photo)

An undercover police officer, who had been marching with anti-police demonstrators, aims his gun at protesters after some in the crowd attacked him and his partner in Oakland, California December 10, 2014. Police said more than 100 demonstrators marched in Berkeley, California, which has a history of social activism. Under cloudy skies, turnout was smaller than earlier in the week, when demonstrators in the area threw rocks at police and shut down a major freeway. (Photo by Noah Berger/Reuters)

Gold bars from the vault of a bank and Swiss one franc coins are seen in this illustration picture taken in Zurich November 20, 2014. The “Save our Swiss gold” proposal, spearheaded by the right-wing Swiss People's Party (SVP), aims to ban the central bank from offloading its reserves and oblige it to hold at least 20 percent of its assets in gold. The referendum is scheduled for November 30. The SVP argues it would secure a stable Swiss franc. (Photo by Arnd Wiegmann/Reuters)

The Smilovichi Felting Factory in Belarus was founded in 1928, when Smilovichi was a small Jewish settlement of craftsmen. Five of those craftsmen organized a small artel (a cooperative association of craftsmen who all live and work together), which produced warm boots called “valenki” for cold weather. Photo: Belarusian workers works at a felt boot factory in Smilovichi, some 35km from Minsk, Belarus, 16 January 2012. (Photo by Tatyana Zenkovich/EPA)

A dejected German Grenadier carrying a machine gun on his shoulder in front of a building on fire during the German retreat in Russia. (Photo by Keystone/Getty Images). 1944

A local resident rests on a bench as Mount Bromo volcano erupts in the background in Ngadisari, Probolinggo, East Java, Indonesia January 5, 2016. (Photo by Darren Whiteside/Reuters)

A folk performer (front R) with make-up and props takes part in a “Blood Shehuo” parade, during a performance in Linyi county, Shanxi province March 21, 2015. “Shehuo” is the common name of Chinese traditional activities consisting of folk performances in northern China. The “Blood Shehuo” performers use make-up and props to re-enact scenes of horror in classic Chinese novels like Water Margin. (Photo by Reuters/Stringer)

An Indian Sikh Nihang, or warrior, performs Gatka martial arts skills during a procession at the Golden Temple in Amritsar on January 6, 2014, as part of birth anniversary celebrations of Guru Gobind Singh. The birth anniversary of Guru Gobind Singh, the tenth Sikh guru, is marked on January 6. (Photo by Narinder Nanu/AFP Photo)