A Chinese couple take pictures in an interactive installation art work named “You and Me” on Valentine's Day at 798 Art Zone on February 14, 2012 in Beijing, China. (Photo by Feng Li/Getty Images)

Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge walk hand in hand from Buckingham Palace the day after their wedding to a waiting helicopter as they leave for a secret honeymoon location, on April 30, 2011 in London, England. The marriage of Prince William and Catherine Middleton was led by the Archbishop of Canterbury and was attended by 1900 guests, including foreign Royal family members and heads of state. Thousands of well-wishers from around the world have also flocked to London to witness the spectacle and pageantry of the Royal Wedding. (Photo by John Stillwell - WPA Pool/Getty Images)

A student is assisted by teachers after she fell ill while marching in a parade celebrating Saint Peter's day in Lima, Peru, Monday, June 29, 2015. During the feast day of the Catholic saint, who is the patron saint of fishermen, coastal communities pay homage to St. Peter, whose statue is paraded to the sea and petitions are made to keep their vessels and all who work on them safe. (Photo by Rodrigo Abd/AP Photo)

Officers react at their graduation ceremony during Iraqi Army Day anniversary celebration in Baghdad January 6, 2015. Iraqi Defence Minister Khaled al-Obeidi said on Tuesday that the Iraqi military has started rebuilding after its near total collapse last summer but that the effort is still in its initial phase. (Photo by Ahmad Mousa/Reuters)

Believers burn dried oak branches, which symbolizes the Yule log, on Orthodox Christmas Eve in front of the St. Sava temple in Belgrade, Serbia, January 6, 2016. Serbian Orthodox believers celebrate Christmas on January 7, according to the Julian calendar. (Photo by Marko Djurica/Reuters)

A girl collects drinking water at Dala river outside Yangon, Myanmar March 3, 2016. Some 650 million people, or one in 10 of the world's population, have no access to safe water, putting them at risk of infectious diseases and premature death. Dirty water and poor sanitation can cause severe diarrhoeal diseases in children, killing 900 under-five a day across the world, according to United Nations estimates. (Photo by Soe Zeya Tun/Reuters)

Kira Walkenhorst of Germany (L) signals as Doaa Elghobashy of Egypt (R) watches during the women's Beach Volleyball preliminary pool D game between Ludwig/Walkenhors of Germany and Elghobashy/Nada of Egypt the Rio 2016 Olympic Games at the Beach Volleyball Arena on Copacabana Beach in Rio de Janeiro, Brazil, 07 August 2016. (Photo by Antonio Lacerda/ANSA)

Thailand's Puttita Supajirakul is down on the court after a point during a women's doubles badminton match against the Netherlands at the 2016 Summer Olympics in Rio de Janeiro, Brazil, August 11, 2016. (Photo by Kin Cheung/AP Photo)