A light railway train passes through a residential building on March 18, 2017 in Chongqing, China. Chongqing Rail Transit No.2 and a 19-storey residential building have been built across each other. The railway set its Liziba Station on the sixth to eighth floor in the building with noise reduction equipment. (Photo by VCG/VCG via Getty Images)

Iraqi soldiers from 9th Armoured Division give drops of water to a dehydrated child rescued earlier by soldiers at the frontline, during the ongoing fighting between Iraqi forces and Islamic State militants near the Old City in western Mosul, Iraq June 13, 2017. (Photo by Erik De Castro/Reuters)

Children of the Roma community play as they cool off in a fountain in the main square of Pristina, Kosovo on June 14, 2017. (Photo by Armend Nimani/AFP Photo)

A cyclist drives past a flowering rapeseed field not far from the small Bavarian village of Schoengeising, near Munich, during a nice, warm sunny weather day on May 17, 2017. (Photo by Christof Stache/AFP Photo)

People fly kites during the 2017 Pyostroye Nebo kite festival in Tsaritsyno Park in Moscow, Russia on August 27, 2017. (Photo by Asya Dobrovolskaya/TASS)

People look at a Christmas tree decorated with colourful lights at a residential compound in Beijing on December 8, 2017. (Photo by Nicolas Asfouri/AFP Photo)

A zoo staff feeds crocodiles as visitors look on at the Malabon Zoo in Malabon City, north of Manila, Philippines 21 December 2017. Wearing Santa Claus hats for the upcoming Christmas season, owner Manny Tangco (R, holding megaphone) and some select animals gave visitors a tour of the 28-year-old zoo. (Photo by Rolex Dela Pena/EPA/EFE)

Katy Perry poses backstage during rehearsals for the 2017 MTV Video Music Awards at The Forum on August 25, 2017 in Inglewood, California. (Photo by John Shearer/Getty Images for MTV)