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)

An elderly woman plays an accordion in Moscow, Russia on October 3, 2017. (Photo by Mladen Antonov/AFP Photo)

Nicole Scherzinger at the “The X Factor” TV show, Series 14, Episode 15, Judges' Houses in Sun City, South Africa on October 21, 2017. (Photo by Dymond/Thames/Syco/Rex Features/Shutterstock)

A man takes a photograph of his friend as thick smoke rises from a fire, which broke out at oil wells set ablaze by Islamic State militants before they fled the oil-producing region of Qayyara, Iraq, January 28, 2017. (Photo by Muhammad Hamed/Reuters)

A demonstrator shows her arm with the name “Marielle” written on it, as she performs during a protest against the murder of councilwoman Marielle Franco in Rio de Janeiro, Brazil, Tuesday, March 20, 2018. Franco's murder came just a month after the government put the military in charge of security in Rio, which is experiencing a sharp spike in violence less than two years after hosting the 2016 Summer Olympics. (Photo by Leo Correa/AP Photo)

An ethnic Lisu man dances barefoot on hot charcoal embers to celebrate the annual Knife Pole Festival in Luzhang township of Nujiang Lisu Autonomous Prefecture in Yunnan province, China, March 29, 2018. (Photo by Aly Song/Reuters)

A woman poses for pictures with skulls made of cardboard placed on an altar next to the San Francisco church in Mexico City during the celebration of All Souls Day on November 2, 2015. (Photo by Yuri Cortez/AFP Photo)

Snow covers roofs, streets and the Charles River following a winter blizzard in Boston, Massachusetts January 28, 2015. A powerful blizzard struck Boston and surrounding New England on Tuesday, leaving some 4.5 million people grappling with as much as three feet of snow and coastal flooding. (Photo by Brian Snyder/Reuters)