Staff of a boat restaurant on the Taedong River line up at the entrance as they wait to greet customers Sunday, June 18, 2017, in Pyongyang, North Korea. The boat is berthed along the river, which is the fifth longest river on the Korean Peninsula and runs through the country's capital, Pyongyang. (Photo by Wong Maye-E/AP Photo)

Woman on swings attached to a float during the Sexual Freedom Parade, part of Naughty in N'awlins held in New Orleans, Louisiana, Wednesday July 5th, 2017. These are the photos from inside the world’s largest swinging convention for couples. The exclusive images reveal the unlikely couples who like to engage in sexual relations with other people besides their partners – and show that swinging is more ‘normal’ than you think. (Photo by Mathew Growcoot/News Dog Media)

A common kingfisher sits on a branch of a tree after catching an insect in Allahabad, India, Sunday, July 9, 2017. The common kingfisher is a highly territorial bird that has to eat nearly sixty percent of its bodyweight every day. (Photo by Rajesh Kumar Singh/AP Photo)

A couple takes a selfie as Hoa Binh hydroelectric power plant opens the flood gates after a heavy rainfall caused by Talas typhoon in Hoa Binh province, outside Hanoi, Vietnam July 20, 2017. (Photo by Reuters/Kham)

Festival-goers take a bath in a mud pool during the 20th Boryeong Mud Festival on Daecheon beach in Boryeong City, some 190 kilometers west of Seoul, South Korea, 22 July 2017. Tourists flock to the area to experience the beneficial properties of the Boryeong mud, as well as for a variety of entertainment events. The festival runs from 21 until 30 July. (Photo by Jeon Heon-Kyun/EPA/EFE)

This Saturday, July 22, 2017 photo released by Tokyo Zoological Park Society, shows a giant panda cub at Ueno Zoo in Tokyo. The baby panda, born in June, got a check up on Saturday. (Photo by Tokyo Zoological Park Society via AP Photo)

Lightning strikes during a storm over the promenade of Palma de Mallorca, Balearics, Spain, on November 4, 2017. Mallorca and Menorca were in yellow alert because of heavy rain and violent winds. (Photo by Cati Cladera/EPA/EFE)

A photo taken on August 21, 2017 shows girls passing in front of a building with a display of the Soviet state founder Vladimir Lenin Order in Volgograd, Russia. Volgograd Arena will host several cames of the FIFA World Cup 2018. (Photo by Mladen Antonov/AFP Photo)