Children wave Vietnamese and American flags while waiting for arrival of U.S. President Barack Obama (not pictured) before a welcoming ceremony at the Presidential Palace in Hanoi, Vietnam May 23, 2016. (Photo by Reuters/Kham)

Labourers break fast outside a shop in a market on the first day of the Muslim holy month of Ramadan in Karachi, Pakistan June 7, 2016. (Photo by Akhtar Soomro/Reuters)

A hungry cow smiles for the camera in Salzburg, Austria. One of a series of funny animal mugshots taken by Chanel Cartell and Stevo Dirnberger during their travels around the globe. (Photo by Chanel Cartell/Stevo Dirnberger/Rex Features/Shutterstock)

Mongolian President Tsakhiagiin Elbegdorj (C) walks towards the media after casting his vote for the parliamentary elections at a polling station in Ulaanbaatar, Mongolia, June 29, 2016. (Photo by Jason Lee/Reuters)

Pakistani passengers ride on crowded train returning from their hometown and villages after celebrating the Eid al-Fitr holiday to mark the end of the Muslim holy fasting month of Ramadan, to Lahore, Pakistan, Monday, July 11, 2016. (Photo by K.M.Chaudary/AP Photo)

Sara White, dressed as Ginny Weasley, a fictional character in J. K. Rowling's Harry Potter series, poses for portrait at the launch of “Harry Potter and the Cursed Child” at Foyles book store on July 30, 2016 in London, England. The script book of the play of the same name, which is on at Palace Theatre, billed as the eighth Harry Potter story, is on sale from midnight tonight. (Photo by Rob Stothard/Getty Images)

A pupil of the Dao ethnic tribe returns home from school along a hillside path at Suoi Thau village in Hoang Su Phi district of Vietnam's northern province of Ha Giang, located at the border with China, September 18, 2015. (Photo by Reuters/Kham)

Evel Knievel is shown in his rocket before his failed attempt at a highly promoted 3/4-mile leap across Snake River Canyon in Twin Falls, Idaho, on September 8, 1974. The jump failed when the parachute on his rocket malfunctioned, opening prematurely. Knievel was uninjured. (Photo by AP Photo)