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)

Piper Hoppe, 10, from Minnetonka, Minnesota, holds a sign at the doorway of River Bluff Dental clinic in protest against the killing of a famous lion in Zimbabwe, in Bloomington, Minnesota July 29, 2015. A Zimbabwean court on Wednesday charged a professional local hunter Theo Bronkhorst with failing to prevent an American from unlawfully killing “Cecil”, the southern African country's best-known lion. The American, Walter James Palmer, a Minnesota dentist who paid $50,000 to kill the lion, has left Zimbabwe. He says he did kill the animal but believed the hunt was legal and that the necessary permits had been issued. (Photo by Eric Miller/Reuters)

Two stallions confront each other at a horse fighting contest in Rongshui, China. More than 30 horses from surrounding regions took part in the traditional activity of the Lantern festival. (Photo by China Foto Press)

A picture made available on 08 July 2015 showsa lightning strikes during a heavy storm over Poznan in the night of 07 July 2015. Severe storms passed last night over Poland causing lots of damages to buildings, trees, electricity and railway tractions. (Photo by Lukasz Ogrodowczyk/EPA)

Women compare their bikini marks after sunbathing on a terrace to have the perfect bikini line (“marquinha” in Portuguese), at the Erika Bronze spa in Rio de Janeiro, Brazil, November 17, 2016. Women start arriving at the spa between 7am and 8am and will tan for approximately 3 hours. (Photo by Pilar Olivares/Reuters)

A British Museum representative poses for photographs next to Andy Warhol's “Mao”, left, and Jim Dine's “Drag: Johnson and Mao” which feature in “The American Dream: pop to the present” exhibition during a media photocall at the British Museum in London, Monday, March 6, 2017. The exhibition, which opens to the public from March 9 and runs until June 18, charts modern and contemporary print making. (Photo by Matt Dunham/AP Photo)

Two holidaymakers amuse themselves with a porter's trolley whilst waiting for their train at Euston Station, London, 5th August 1939. (Photo by A. J. O'Brien/Fox Photos/Getty Images)

A plane battling the Ferguson Fire passes the setting sun in unincorporated Mariposa County Calif., near Yosemite National Park on Sunday, July 15, 2018. (Photo by Noah Berger/AP Photo)