Yoga students take a class with Nigerian Dwarf goats held by the 'Hello Critter Goat Yoga' team at the Golden Road Pub in Los Angeles, California on May 7, 2018. The goat yoga fitness craze is sweeping the United States with classes now held in pubs, farms and halls across the country. (Photo by Mark Ralston/AFP Photo)

Rwandan refugees cross the Rusumo border to Tanzania from Rwanda carrying their belongings, goats, mattresses and cows, May 30, 1994. The bloodshed that claimed 800,000 Tutsi and moderate Hutu lives began 25 years ago on April 7, 1994, when a plane carrying Rwandan President Juvenal Habyarimana, Burundi President Cyprien Ntaryamira and a French air crew was shot down. (Photo by Jeremiah Kamau/Reuters)

A truck carrying gold miners across the Sahara desert to far northern Niger drives outside Agadez, Niger, May 9, 2016. (Photo by Joe Penney/Reuters)

A Christie's auction house employee wears The Rosebury pearl and diamond tiara, bracelet and brooch on June 6, 2011 in London, England. The jewels, which formerly belonged to Hannah, Countess of Rosebury, feature in Christie's “Important Jewels” sale which take places in London on June 8, 2011. (Photo by Oli Scarff/Getty Images)

A Banksy decorated truck entitled “Laugh now but one day we'll be in charge” is displayed for sale on October 6, 2011 in London, England. The Volvo FL6 lorry was decorated by British street artist Banksy for a millennium party for Turbozone, pyrotechnic touring circus. It will be offered for auction in London this month. (Photo by Peter Macdiarmid/Getty Images)

A girl laughs while unloading her boat of produce at a market in Ganvie on January 6, 2012 in Cotonou, Benin. Often called the Venice of Africa, Ganvie is a stilted fishing village on Lake Nokoue, near Cotonou in Benin, the largest such village in Africa, and home to approximately 20,000 residents. (Photo by Dan Kitwood/Getty Images)

Visitors of the world's longest tree top walk between the trees of the Bavarian forest on November 6, 2009 in Neuschoenau, Germany. The path, 1300 meters long and in 8 to 25m height, winds up to an impressive tower with a height of 44 meters. The wooden construction is integrated into the forest and delivers a natural experience. (Photo by Miguel Villagran/Getty Images)

Police take part in a role play exercise as they clear a protest on top of a train during training on March 6, 2012 in Oxenhope, England. A new team of specialist officers set up to deal with searches and policing at a height, such as on top of a train, undergo training exercise in Oxenhope, West Yorkshire. (Photo by Bethany Clarke/Getty Images)