In this May 1, 2016 photo, a reluctant donkey is alternately pushed and pulled and enticed with carrots toward town hall in order to be dressed for the costume competition at the annual donkey festival in Otumba, Mexico state, Mexico. Otumba was an important donkey market during Spanish colonial times, standing at the crossroads of major roads leading to Mexico City, where the beasts pulled heavy loads and carried travelers. Today, however, farmers use tractors and pickup trucks, and the donkey population is in decline. (Photo by Rebecca Blackwell/AP Photo)

A pair of tigers soak in a shallow pool at Tiger Temple, a Buddhist monastery where paying visitors can interact with young adult tigers, in Kanchanaburi, Thailand, March 16, 2016. The attraction, near the Myanmar border, started collecting the animals 15 years ago when villagers brought an injured tiger cub to the local abbot, who agreed to care for it. Today there are nearly 150 tigers at the monastery. (Photo by Amanda Mustard/The New York Times)

Female Naval Academy plebes perform push ups with a twelve foot log on top of them during the annual Sea Trials May 17, 2016 at the Naval Academy in Annapolis, Maryland. The Naval Academy freshman class endures 14 hours of rigorous physical and mental challenges during the annual Sea Trials training exercise as part of the culmination of their freshman year at the academy. (Photo by Win McNamee/Getty Images)

Tourists dressed in yukatas, a light, unlined, summer kimono made of cotton instead of the traditional silk, climb steps to visit a temple on April 27, 2016 in Kyoto, Japan. Now the seventh largest city in Japan, Kyoto was once the Imperial capital for more than one thousand years, it is now the capital city of Kyoto Prefecture and a major part of the Kyoto-Osaka-Kobe metropolitan area. (Photo by Carl Court/Getty Images)

Iraqi pro-government forces fire an anti-tank cannon near al-Sejar village, north-east of Fallujah, on May 25, 2016, as they take part in a major assault to retake the city from the Islamic State (IS) group. Iraqi forces, consisting of special forces, soldiers, police, paramilitary-fighters and pro-government tribesmen, launched a major assault to retake Fallujah, the scene of deadly battles during the US occupation and one of the toughest targets yet in Baghdad's war on the Islamic State group. (Photo by Ahmad Al-Rubaye/AFP Photo)

A 10-year-old boy living on the streets of New Delhi lies down on cascading water of a fountain in the gardens of the India Gate monument on May 20, 2016. The Indian Meteorological Department issued warnings of “severe heat wave” conditions across large parts of India's north and west, including the capital Delhi, where temperatures hit 47 degrees Celsius. (Photo by Roberto Schmidt/AFP Photo)

Colorado Gov. John Hickenlooper shows off his socks--one with Democratic presidential candidate Bernie Sanders and the other with Republican candidate Donald Trump – before entering his former brewpub for a book signing event to mark the release of his autobiography Thursday, May 26, 2016, in Denver. Hickenlooper, who is term-limited, is doing book talk rounds this week, reviving speculation that he is positioning himself to join Hillary Clinton's presidential campaign ticket. (Photo by David Zalubowski/AP Photo)

A worker at the Jabal Saraj cement factory poses for a photograph in Jabal Saraj, north of Kabul, Afghanistan April 19, 2016. In an area desperately short of industry and jobs, local workers hope that the relaunch of the plant in Jabal Saraj, built by Czech engineers in 1957 and closed down by the Taliban in 1995, can show that Afghanistan's shattered industry can climb back to its feet after decades of war and destruction. But the outdated state-owned plant some 75 kilometres outside Kabul also shows how far it has to go before that promise can be achieved and there are serious questions over whether it has a viable future unless a new, modern facility is built to replace it. (Photo by Ahmad Masood/Reuters)