Bangladeshi Muslims travel on the roof of an overcrowded train as they head to their hometowns ahead of Eid al-Adha in Dhaka, Bangladesh, Friday, September 1, 2017. The festival commemorates the story of Abraham and his readiness to sacrifice his son as an act of obedience to God, who provided a lamb to be used instead. (Photo by Bernat Armangue/AP Photo)

In this November 20, 2017 photo, Indian kushti wrestlers fight in the ring, during their daily training at an akhada, a kind of wrestling hostel at Sabzi Mandi, in New Delhi, India. Like many traditions in rapidly modernizing India, kushti wrestling faces the threat of being left behind. But for many poor families, the ancient sport provides a glimmer of hope. (Photo by Dar Yasin/AP Photo)

A handout photo provided by the Police department in Lippe on 01 June 2015 of a British “Challenger 2” tank after it rolled over a car's front in Lippe, Germany, 01 June 2015. Police reported that a 18-year old female driving beginner from Detmold apparently overlooked a convoy of tanks when she turned left onto the Panzeringstrasse (lit. Tank Ring Road). (Photo by EPA/Polizei Lippe)

This undated handout picture made available on February 3, 2016 and provided by Russia's punk band Рussy Riot shows Рussy Riot frontwoman Nadezhda Tolokonnikova performing in the band's new music video titled “Chaika” in Moscow. Russian punk band Рussy Riot, which became a symbol of resistance for a church performance slamming President Vladimir Putin, released a new protest song on February 3 mocking a senior official for alleged corruption. Titled “Chaika”, the satirical song and accompanying video take aim at prosecutor general Yury Chaika, whose two sons have been accused of using their father's position to accrue large fortunes. (Photo by Andrey Noskov/AFP Photo/Russian Punk Band Рussy Riot)

Two boys in the Gorbals area of Glasgow, UK on January 31, 1948. The Gorbals tenements were built quickly and cheaply in the 1840s, providing housing for Glasgow's burgeoning population of industrial workers. Conditions were appalling; overcrowding was standard and sewage and water facilities inadequate. The tenements housed about 40,000 people with up to eight family members sharing a single room, 30 residents sharing a toilet and 40 sharing a tap. By the time this photograph was taken 850 tenements had been demolished since 1920. Redevelopment of the area began in the late 1950s and the tenements were replaced with a modern tower block complex in the sixties. (Photo by Bert Hardy/Getty Images)

A handout image provided by the New Zealand Defence Force shows aid supplies being unloaded by Fijian soldiers from an Royal New Zealand Airforce C-130 Hercules plane in Suva, Fiji, 23 February 2016. Tool kits, generators, ration packs, water containers and chainsaws make up part of the New Zealand relief following Tropical Cyclone Winston. The death toll from the cyclone that hit Fiji over the weekend climbed to 29, local media reported ON 23 February. Cyclone Winston, the most powerful storm in Fiji's history, battered the country's main island of Viti Levu and other smaller surrounding islands on Saturday, the Fiji Broadcasting Corporation reported. (Photo by Sam Shepherd/EPA/NZ Defence Force)

A model poses beside the Porsche Hybrid during the media day of the Shanghai International Automobile Industry Exhibition at Shanghai New International Expo Center on April 19, 2011 in Shanghai, China. The 14th Shanghai International Automobile Industry Exhibition (Auto Shanghai 2011) will be held from April 21 to 28 with the theme of “Innovation For Tomorrow”. About 2,000 carmakers and parts providers from 20 countries are due to showcase 1,100 car models, 75 of which makes their world premieres in the auto show. (Photo by Feng Li/Getty Images)

The land-robot “teleMAX” of German company telerob stands next to soldiers during a trial at the German army base on May 18, 2010 in Hammelburg, Germany. ELROB provides an overview of the current state of affairs in European unmanned system technology and to evaluate commercial off-the-shelf products for military use. It is to show what is feasible in robotics, to support technological developments in Europe, and to find solutions for the current military challenges. (Photo by Ralph Orlowski/Getty Images)