Serena Williams of the U.S. serves during her first round match against Italy's Camila Giorgi at the Australian Open tennis tournament at Melbourne Park, Australia, January 18, 2016. (Photo by Jason O'Brien/Reuters)

Newlyweds take wedding photos hanging from bridge, Yueyang, Hunan province, China on August 9, 2016. They held such a special wedding ceremony on China's Qixi Festival. (Photo by Top Photo Corporation/Rex Features/Shutterstock)

An Afghan woman fills containers with water near her temporary shelter at an internally displaced person's (IDP) camp on the outskirts of Herat, Afghanistan, January 21, 2015. Dozens of families are living in temporary shelters even in harsh winters and most depend on aid distributions by the United Nations High Commissioner for Refugees (UNHCR). (Photo by Jalil Rezayee/EPA)

Members of the Baby Dolls, a traditional Mardi Gras social club, dance during a second line parade honoring music legend Fats Domino, in New Orleans, Wednesday, November 1, 2017. The thousand-strong group marched and danced from Vaughn's Lounge to Domino's former home in the Lower 9th Ward. Domino, a New Orleans native, died this past week. (Photo by Gerald Herbert/AP Photo)

Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

An AH-64D Apache attack helicopter flies in front of a wall of fire during the South Carolina National Guard Air and Ground Expo at McEntire Joint National Guard Base, South Carolina, U.S. on May 6, 2017. (Photo by Jorge Intriago/Reuters/Courtesy Air National Guard)

In this April 7, 2015 photo, a tourist peers through the door of a jail cell inside the now empty Garcia Moreno prison during a guided tour for the public in Quito, Ecuador. According to tour guides, this cell was nicknamed “Los Polillas”, or “The Moths”. Here, in a room designed to hold two prisoners, about 15 inmates with drug addictions were locked in overnight by the prison gangs that controlled daily life. The locked-in prisoners were also known to prostitute themselves to get access to drugs. (Photo by Dolores Ochoa/AP Photo)