This 2014 series Shanghai Tian Wa saw Chinese photographer Liu Tao train his lens on two distinct districts in Shanghai. Here: “Shanghai Tian Wai №26, 2014”. (Photo by Liu Tao/The Guardian)

A dog trainer works with a previously abandoned dog at a police centre in Saltillo, Mexico March 4, 2016. Stray dogs are adopted by the police from a municipal anti-rabies centre and then trained to help the police patrol the streets, and search for drugs, explosives and weapons. (Photo by Daniel Becerril/Reuters)

Revelers gather on a commuter train platform of the HVV city public transportation system to drink alcohol on September 30, 2011 in Hamburg, Germany. Thousands of people participated in the event dubbed the “HVV Abschiedstrinken” (HVV Farewell Drink) that was organized through Facebook and is meant to celebrate the last day before a ban on alcohol consumption goes into effect on the city's public transport. (Photo by Joern Pollex/Getty Images)

Tree trunks lie on the railtracks that will be used to transport nuclear waste on November 25, 2011 in Leitstade, near Metzingen, Germany. A train carrying the Castor containers of processed, spent nuclear fuel started from La Hague in France Wednesday for its journey to the Gorleben temporary nuclear waste storage facility in Germany, and thousands of protesters are expected to attempt to blockade the route. (Photo by Carsten Koall/Getty Images)

Key Gompa (also spelled Ki, Kye or Kee) is a Tibetan Buddhist monastery located on top of a hill at an altitude of 4,166 metres (13,668 ft) above sea level, close to the Spiti River, in the Spiti Valley of Himachal Pradesh, Lahaul and Spiti district, India. It is the biggest monastery of Spiti Valley and a religious training centre for Lamas. It reportedly had 100 monks in 1855.

An activist kicks the shields of the military police officers during a demonstration in the military zone of the 27th infantry battalion in Iguala, Guerrero, January 12, 2015. Activists and relatives of the 43 missing trainee teachers from Ayotzinapa's teacher training college broke into the military zone, located less than a mile from where the students went missing, in an attempt to look for the missing students.The remains of only one of the 43 students has been identified so far. (Photo by Jorge Dan Lopez/Reuters)

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)

People gather at the site of a train derailment near Beni Suef, Egypt, Thursday, February 11, 2016 that injured dozens of people were injured as it was traveling north toward Cairo. Railroad accidents due to negligence are common in Egypt. Egyptians have long complained that the government has failed to deal with the country's chronic transport problems. (Photo by Samer Abdallah/AP Photo)