Palestinian bedouin shepherds pull their lambs into the water to wash them, in Gaza City, on April 29, 2016. Every year before the beginning of the summer, shepherds wash their herds in the sea. (Photo by Mohammed Abed/AFP Photo)

Mara Salvatrucha (MS) gang members show off their weapons in the Las Victorias district of San Salvador. In March 2012, the two largest gangs in El Salvador - the Mara Salvatrucha (MS) and the Barrio 18 (M18) - agreed on a truce following secret negotiations between gang leaders in prison which were mediated by a bishop and a former rebel leader. It is unclear whether the decision was the idea of the gangs themselves or whether they were encouraged by the government. (Photo by Adam Hinton)

Super-cell thunderstorms, whirling tornados and lightning bolts illuminating the sky – these photos capture the terrifying brilliance of American storms. (Photo by Brandon Goforth/Solent News & Photo Agency)

Meatball, a bulldog, poses in a tuxedo at the Tompkins Square Halloween Dog Parade on October 20, 2012 in New York City. Hundreds of dog owners festooned their pets for the annual event, the largest of its kind in the United States. (Photo by John Moore)

Undated UK Ministry of Defence handout photo of an RAF Tornado GR4 which has been painted in Gulf War “desert pink” paint scheme to honour the aircraft type's almost continuous operational service since the Royal Air Force helped liberate Kuwait from Saddam Hussein's forces, taken by SAC Rose Buchanan, which has been shortlisted for the general public to pick their favourite RAF Image of the Year. (Photo by SAC Rose Buchanan/MoD Crown Copyright/PA Wire)

Local residents crowd a swimming pool during a hot weather in Suining, Sichuan province, 27 July 2008. (Photo by Reuters/Stringer)

Hillary Clinton waves to a selfie-taking crowd at a recent campaign event in Orlando, Florida on September 26, 2016. (Photo by Barbara Kinney/Hillary for America)

Daniela Burza, 45, wears a Nasty Woman t-shirt and a mask of U.S. Democratic presidential nominee Hillary Clinton as she competes during the Haunted Heats Halloween Surf Contest in Santa Monica, California, U.S., October 29, 2016. (Photo by Lucy Nicholson/Reuters)