A Palestinian boy takes part in a military-style summer camp being held by the Islamic Jihad movement during the youngsters' summer school vacation in Khan Younes town, in the southern Gaza Strip, 13 July 2016. Thousands of youngsters between the age of six and 16 can participate in the summer camp where they receive military as well as religious training. (Photo by Hatem Omar/EPA)

In this Wednesday, November 15, 2012 file photo, a young girl in her colorful dress reaches out to greet a Pakistani policeman securing the road outside Kainat Riaz's home in Mingora, Swat Valley, Pakistan. (Photo by Anja Niedringhaus/AP Photo)

A villager jumps during “Los Sidros y Las Comedias”, a traditional festival in Spain's northern village of Valdesoto, January 8, 2017. (Photo by Eloy Alonso/Reuters)

Lisandra Perez, 7, practices in his house before his flute lesson at the Integral System of Artistic Education for Social Inclusion (SIFAIS) center in the poor neighborhood of La Carpio, Costa Rica October 8, 2015. SIFAIS center is developing a social program with the help of 156 volunteers who teach art, music, sports and education, for children and youth living in La Carpio, known for being the home to gangs, violence, drugs and social vulnerability, according to the centre. (Photo by Juan Carlos Ulate/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)

A masked Palestinian uses a board to protect himself during clashes with Israeli forces which occurred shortly before Palestinian leader Mahmoud Abbas' speech to the the United Nations General Assembly, on September 23, 2011 in Qalandia, West Bank. (Photo by Ilia Yefimovich/Getty Images)

A protester uses his laptop computer in the “Occupy LSX” camp outside St. Paul's Cathedral ahead of a demonstration against higher tuition fees and privatisation in universities on November 9, 2011 in London, England. Around 4000 police officers are on duty and are to be allowed to deploy baton rounds if needed. The march is expected to finish at London Wall in the heart of the capital's financial district. (Photo by Oli Scarff/Getty Images)

A UCLA student is arrested by Los Angeles Police Department officers after she attempted to escape after eleven student protesters sat in circle in middle of the Westwood and Wilshire boulevard intersection as part of a protest of bank practices and rising fees at public universities on November 9, 2011 in Los Angeles, California. The protest organized by ReFund California was one of several planned at universities around the state. (Photo by Kevork Djansezian/Getty Images)