A Palestinian youth jumps with a sword as he demonstrates his ninja-style skills for the photographer in front of the ruins of buildings, that were destroyed in 2014 war, in the northern Gaza Strip January 29, 2016. The youths, who have been receiving martial arts training at local clubs in Gaza for the past two years, decided to form a team to hold regular shows in the hope that the publicity generated will eventually lead to them being invited to participate in international contests. (Photo by Mohammed Salem/Reuters)

A child coughs as migrants and refugees run away after Macedonian police fired tear gas at hundreds of Iraqi and Syrian migrants who tried to break through the Greek border fence in Idomeni, on February 29, 2016. Greek police said more than 6,000 people were massed at the border, in a buildup triggered by Austria and Balkan states capping the numbers of migrants entering their territory. (Photo by Louisa Gouliamaki/AFP Photo)

A boy sits in a canoe in front of a shed built on a raft in the Makoko fishing community on the Lagos Lagoon, Nigeria February 29, 2016. In Makoko, a sprawling slum of Nigeria's megacity Lagos, a floating school capable of holding up to a hundred pupils has since November brought free education to the waterways known as the Venice of Lagos. It offers the chance of social mobility for youngsters who, like most of the city's 21 million inhabitants, lack a reliable electricity and water supply and whose water-based way of life is threatened by climate change as well as rapid urbanisation. (Photo by Akintunde Akinleye/Reuters)

Fresa, 5, stands inside the dog shelter “Santuario Milagros Caninos” on the outskirts of Mexico City August 29 2014. Fresa underwent reconstructive surgery after her previous owners hacked off half of her snout with a sharp object, possibly a machete, according to surgeon Jesus Paredes. After neighbours found Fresa wandering on the streets, they handed her over to a shelter where Paredes performed a three-hours intervention to enable her to breathe again through her nostrils, to remove her protruding jaw and reconstruct the lips with flaps of skin and mucous. (Photo by Edgard Garrido/Reuters)

Harry Potter collectible busts are displayed in the home of Menahem Asher Silva Vargas, after he was presented with a Guinness World Record title certificate for the largest collection of Harry Potter memorabilia, in Mexico City, Monday, September 29, 2014. Silva's collection consists of more than 3000 individual items, including trading cards, wands, and books in multiple languages. (Photo by Rebecca Blackwell/AP Photo)

A box of 36 coloured pencils as photographed in a studio with an illustrative price tag of $115 (US dollars), equivalent to the Bs. 725 (bolivars) that it costs on average to purchase in Caracas at the official exchange rate of 6.3 bolivars per dollar, in Caracas September 29, 2014. Venezuela's economic crisis has led to some shocking and surreal price distortions that hit people's buying power dramatically. (Photo by Carlos Garcia Rawlins/Reuters)

Sculptor Jiri Genzer of the Czech Republic carves an ice sculpture at the Disney Dreams Ice Festival in Antwerp November 27, 2014. Some 60 artists from all over the world participated in the festival, making sculptures out of around 500 tonnes of ice. The festival will open on November 29 until January 11, 2015. (Photo by Yves Herman/Reuters)

A group of people wearing full solid-coloured bodysuits walk along a promenade as they take part in a street art performance in Bat Yam, near Tel Aviv, Israel August 29, 2015. Some 40 people participated on Saturday in the performance, initiated by a group of artists called Prizma Ensemble, as part of the city's annual international street art and street theatre festival. The group says the performance deals with concepts of identity and movement in public spaces. (Photo by Amir Cohen/Reuters)