This combination of April 15, 2013 and April 2, 2014 photos show a police officer clearing Boylston Street following a bomb blast near the finish line of the 2013 Boston Marathon, and pedestrians crossing at the same corner nearly a year later in Boston. (Photo by Charles Krupa/AP Photo)

Dakar Rally, 2017 Paraguay-Bolivia-Argentina Dakar rally, 39th Dakar Edition, First stage from Asuncion, Paraguay to Resistencia, Argentina on January 2, 2017. Adrien Metge of France pushes his Sherco. (Photo by Ricardo Moraes/Reuters)

A National Bolivarian Police officer rescues a man who was being attacked by protesters, who then threw rocks at them, during a protest demanding food a few blocks from Miraflores presidential palace in Caracas, Venezuela, Thursday, June 2, 2016. Venezuela is seeing rising frustration with widespread food shortages and triple-digit inflation. (Photo by Fernando Llano/AP Photo)

A female participant of the Bela Negara – “defend the nation” – programme applies camouflage face paint on another participant's face at a training centre in Rumpin, Bogor, West Java, Indonesia June 2, 2016. (Photo by Darren Whiteside/Reuters)

Tree trunks and rocks are set up to support a leaning wall of Li Yonghua's damaged cave house in an area where land is sinking next to a coal mine, in Helin village of Xiaoyi, China's Shanxi province, August 2, 2016. (Photo by Jason Lee/Reuters)

Visitors visit the upside-down family size house in Taipei, Taiwan, 23 February 2016. The three story upside-down family size house attracts hundreds of visitor’s who are amused with the exhibit. According to the organizers, the total cost of the construction is around 600,000 US Dollars and took 2 months to complete. (Photo by Ritchie B. Tongo/EPA)

People participate in a pillow fight to mark International Pillow Fight Day in the Heroes' Square, in central Budapest, Hungary, Saturday, April 2, 2016. The Pillow Fight Day attracts tens of thousands people in more than 100 cities all over the World each year. ((Photo by Zoltan Balogh/MTI via AP Photo)

A participant takes part in the annual Jack In The Green parade involving hundreds of costumed revellers joining a four hour procession culminating in the traditional “slaying” of a Jack character to “unleash the spirit of summer” on the May Day week end, in Hastings, southern Britain, May 2, 2016. (Photo by Toby Melville/Reuters)