Street fighting in Berlin between Government troops and Spartacists, during the Spartacist uprising which followed Germany's defeat in World War I. (Photo by Keystone/Getty Images). 1919

In this September 10, 1977, file photo, from left, Hua Guofeng, Chinese Communist Party (CCP) chairman and Mao Zedong's immediate successor; Ye Jianying, CCP vice chairman and future ceremonial head of state; Deng Xiaoping, no formal titles at the time but soon to emerge as paramount leader during the reform era; Li Xiannian, CCP vice chairman and future president; Wang Dongxing, head of the leadership bodyguard unit who helped topple the Gang of Four, view the body of later Chinese leader Mao Zedong in Beijing. (Photo via AP Photo)

A member of Red Noses Clowndoctors entertains migrants before their departure to Austria at a registration center in Dobova, Slovenia, December 27, 2015. (Photo by Srdjan Zivulovic/Reuters)

A combination photo shows the faces of various attendees of New York Comic Con in Manhattan, New York, October 8, 2015. The event draws thousands of costumed fans, panels of pop culture luminaries and features a sprawling floor of vendors in a space equivalent to more than three football fields at the Jacob Javits Convention Center on Manhattan's West side. (Photo by Andrew Kelly/Reuters)

Chinese women wear face-kinis as they walk in to the water to swim at the beach on August 20, 2014 in the Yellow Sea in Qingdao, China. The locally designed mask is worn by many local women to protect them from jellyfish stings, algae and the sun's ultraviolet rays. (Photo by Kevin Frayer/Getty Images)