Students attend a stewardess skill training for the upcoming 2017 entrance examination for art majors in colleges in Luoyang, central China's Henan Province, January 4, 2017. Along with how to stand, how to sit is also covered in these classes. (Photo by Li Bo/Xinhua/Barcroft Images)

A Palestinian youth practices his parkour skills at Shati refugee camp in Gaza City April 27, 2014. (Photo by Mohammed Salem/Reuters)

Iranians flash the victory sign from their car while celebrating on a street in northern Tehran, Iran, Thursday, April 2, 2015, after Iran's nuclear agreement with world powers in Lausanne, Switzerland. The United States, Iran and five other world powers on Thursday announced an understanding outlining limits on Iran's nuclear program so it cannot lead to atomic weapons, directing negotiators toward achieving a comprehensive agreement within three months. (Photo by Ebrahim Noroozi/AP Photo)

Andy Swan “Zippy the Clown” from Sacramento, California, drives his “elelphant” car during a break at the 2011 Clowns of America International Convention on April 15, 2011 in Anaheim, California. Several hundred clowns, from all over the United States and from as far as Puerto Rico and Germany, are attending the convention to compete in skits and hone their skills in the art of balloon-making and face-painting. (Photo by Kevork Djansezian/Getty Images)

Kritchaya “Lolita” Boonhor (R) curls her eyelashes in ladyboy Candy's (L) room while she chats her about her boyfriend, in Bangkok, Thailand, 27 November 2017. Most things in life are a question of negotiation. Lolita is a woman, that was not to be negotiated. What needed to be negotiated was how she was perceived by those around her. And that negotiation was one that took time and effort. (Photo by Lola Levan/EPA/EFE)

A sales woman of a fish shop shows king crabs to a customer and negotiates the price in Noryangjin Fish Market is seen on August 1, 2015 in Seoul, South Korea. Noryangjin Fish Market was established in 1927 as Gyeongseong Susan in Jung-gu near Seoul Station and moved to its current location in 1971. (Photo by Shin Woong-jae/The Washington Post)

Women pose for a picture at Havana city, Cuba, March 17, 2016. Obama arrives in Havana on Sunday for a historic visit that seals a rapprochement he and Cuban President Raul Castro agreed in December 2014 after 18 months of secret negotiations. (Photo by Ivan Alvarado/Reuters)