Cuban soldiers receive combat training at the Cadets School “Antonio Maceo” November 28, 2001, 30 kilometers East of Havana. (Photo by Jorge Rey/Getty Images)

Travellers stop to take a second glance at a model of a giant lady with her head stuck in a photo booth being exhibited in Victoria train station on September 21, 2007 in London, England. (Photo by Cate Gillon/Getty Images)

An instructor from the Tianjiao Special Guard/Security Consultant Ltd. Co, smashes a bottle over a female recruit's head during a training session for China's first female bodyguards in Beijing January 13, 2012. (Photo by David Gray/Reuters)

A man carries his wife on his back as they make their way with their luggage along a flooded tunnel to catch their train, after heavy rainfall hit Jinhua, Zhejiang province, China, July 21, 2015. (Photo by Reuters/China Daily)

In this photo taken on Thursday, July 23, 2015 migrants enter a train to Serbia at the railway station in the southern Macedonian town of Gevgelija. The country has become a major transit route for thousands of Middle Eastern and African refugees and migrants who cross over from Greece and then continue into Serbia. (Photo by Boris Grdanoski/AP Photo)

People try to board an overcrowded passenger train as they travel home to celebrate Eid al-Fitr festival, which marks the end of the Muslim holy fasting month of Ramadan, at a railway station in Dhaka, Bangladesh, July 5, 2016. (Photo by Adnan Abidi/Reuters)

An exile Tibetan monk gestures as he makes a point in a dialectics debate with another monk, sitting right, at the Kirti monastery in Dharmsala, India, Monday, January 18, 2016. The debate is an essential part of their training as Buddhist monks. (Photo by Ashwini Bhatia/AP Photo)

An old locomotive train that was used for transporting coal is preserved as a monument at Ny-Alesund, in Svalbard, Norway, October 11, 2015. A Norwegian chain of islands just 1,200 km (750 miles) from the North Pole is trying to promote new technologies, tourism and scientific research in a shift from high-polluting coal mining that has been a backbone of the remote economy for decades. (Photo by Anna Filipova/Reuters)