People pause at a memorial set up for victims of a mass shooting in Las Vegas, Nev., on Tuesday, October 3, 2017. A gunman opened fire on an outdoor music concert on Sunday. It was the deadliest mass shooting in modern U.S. history, with dozens of people killed and hundreds injured, some by gunfire, some during the chaotic escape. (Photo by John Locher/AP Photo)

In 2013, the United Nations General Assembly officially designated November 19 as World Toilet Day, which is coordinated by UN-Water in collaboration with governments and partners. Here: An open-air toilet and a hot spring shower are seen in the middle of nowhere on the road to the Krafla geothermal power station and lava fields, near Reykjahlid and Lake Myvatn in northeastern Iceland, on August 19, 2012. (Photo by Mariana Suarez/AFP Photo)

A performer poses during celebrations after Rahul Gandhi, newly elected president of India's main opposition Congress party, took charge as the president during a ceremony outside the party's headquarters in New Delhi, India, December 16, 2017. (Photo by Altaf Hussain/Reuters)

Students of the Krasnoyarsk choreographic college Anastasia Shevtsova (R) and Yulia Lyakhovykh do leg-splits as they study for an exam and a performance by the graduates at the State Theatre of Opera and Ballet, at the college's campus in the Siberian city of Krasnoyarsk, Russia, May 4, 2017. (Photo by Ilya Naymushin/Reuters)

Participants dance during the West Indian Day Parade in the Brooklyn borough of New York September 5, 2016. The Labor Day Carnival (or West Indian Carnival) is an annual celebration held on American Labor Day (the first Monday in September) in Crown Heights, Brooklyn, in New York City. (Photo by Eric Thayer/Reuters)

People ride on a truck as they return to their families ahead of the Eid al-Adha festival in Khartoum September 11, 2016. (Photo by Mohamed Nureldin Abdallah/Reuters)

Street vendors carry chickens for sale at Kawran Bazar in Dhaka, Bangladesh January 25, 2017. (Photo by Mohammad Ponir Hossain/Reuters)

Revelers dance at the Old Settler's Music Festival in Driftwood, Texas, U.S. on April 22, 2017. (Photo by Mohammad Khursheed/Reuters)