Aegean airlines air hostesses take selfies after a news conference in Athens, Wednesday, March 28, 2018. In a deal worth up to $5 billion, Greek airline Aegean says it will buy 30 new Airbus aircraft, with the option of an additional 12, to upgrade its fleet as the country expects to break tourism records. The signing of the final purchase agreement is expected in June. (Photo by Petros Giannakouris/AP Photo)

Germany's Angelique Kerber reacts after popping a bottle of champagne, a day following her win in the final match at the Australian Open tennis tournament, at the Government House in Melbourne, Australia, January 31, 2016. (Photo by Issei Kato/Reuters)

An undated handout picture made available on 29 April 2016 by the Toronga Zoo shows a baby echidna making a remarkable recovery after being attacked by chickens in a family's backyard at the Taronga Zoo in Sydney, Australia. (Photo by EPA/Taronga Zoo)

Labourers work at a garment factory in Bac Giang province, near Hanoi October 21, 2015. Vietnam's textiles and footwear would gain strongly from the TPP, after exports of $31 billion last year for brands such as Nike, Adidas, H&M, Gap, Zara, Armani and Lacoste. (Photo by Reuters/Kham)

Drastic inequality is by no means new in New York. Jacob A. Riis was called a muckraker after he chose to spotlight the city’s poverty at the turn of the 20th century by photographing it. Here: Sweatshop in Hester Street, 1889-1890. (Photo by Jacob A. Riis/Museum of the City of New York, Gift of Roger William Riis)

U.S. players push head coach Adam Krikorian into the pool after they defeated the Netherlands in their women's water polo gold medal match during the Aquatics World Championships in Kazan, Russia, August 7, 2015. (Photo by Michael Dalder/Reuters)

A farmer tends to his field as Mount Sinabung releases pyroclastic flows in Tiga Pancur, North Sumatra, Indonesia, Saturday, June 13, 2015. The volcano, which was put on it highest alert level last week, has sporadically erupted since 2010 after being dormant for 400 years. (AP Photo/Binsar Bakkara)

A mine detection rat is given banana as a reward after successfully identifying an inactive mine on July 2, 2015 in Siem Reap, Cambodia. The Cambodian Mine Action Center (CMAC) working with the Belgian NGO APOPO has recently begun testing the feasability of using large mine detection rats from Tanzania to help clear fields of mines and unexploded ordnance in one of the most bombed and mined countries in the world. (Photo by Taylor Weidman/Getty Images)