People look at a man, who residents said was killed by al Qaeda militants, hanging on a bridge in Yemen's southeastern city of Mukalla June 17, 2015. Al Qaeda militants in Yemen killed two alleged Saudi spies, residents said, accusing them of planting tracking devices which enabled the assassination of the group's leader in a suspected U.S. drone strike. (Photo by Reuters/Stringer)

The sun rises beside St Mary's Lighthouse in Whitley Bay, Tyne and Wear, as the unseasonably cool weather continues on Thursday, April 28, 2016. (Photo by Owen Humphreys/PA Wire)

Two sheep fight in a competition in Zhangjiakou, Hebei province, China on August 1, 2017. (Photo by Reuters/China Stringer Network)

A woman plays with her three dogs at the beach after sunset in Del Mar, California, USA on November 10, 2017. (Photo by Mike Blake/Reuters)

One of the last incoming trains arrives outside the main train station after Deutsche Bahn cancelled all train traffic in Germany due to heavy storms, Frankfurt, Germany, Thursday, January 18, 2018. (Photo by Michael Probst/AP Photo)

In this November 12, 2015, file photo, Mt. Everest is seen from the way to Kalapatthar in Nepal. An American climber has died near the summit of Mount Everest and an Indian climber is missing after heading down from the mountain following a successful ascent, expedition organizers said Sunday. (Photo by Tashi Sherpa/AP Photo)

England fan stripped down to her underwear and jumped in the canal in Birmingham, United Kingdom after team lose the 2018 World Cup semi- final against Croatia in Moscow on July 11, 2018. (Photo by Caters News Agency)

Gas-masked men of the British Machine Gun Corps with a Vickers machine gun during the first battle of the Somme, 1916. (Photo by General Photographic Agency/Getty Images)