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)

U.S. Air Force wounded warrior, Capt. Sarah Evans, jumps rope in a gym in San Antonio, Texas. Evans was diagnosed with cancer while deployed to Afghanistan and was medically evacuated back to the United States where her leg was amputated. (Photo by Master Sgt. Jeffrey Allen/U.S. Air Force)

Musafir, a pet monkey, eats sweets on a pavement in Kolkata, India, June 9, 2016. (Photo by Rupak De Chowdhuri/Reuters)

Tatiana Osorio, of Orlando, cries while giving blood at the OneBlood blood center near the mass shooting at a nightclub, June 13, 2016, in Orlando, Fla. Osorio lost three friends in the shooting. (Photo by David Goldman/AP Photo)

A sign that reads “No more massacres LGBT” is seen to remember the victims of the Pulse nightclub mass shooting in Orlando, near the U.S. Embassy in Mexico City, Mexico, June 14, 2016. (Photo by Edgard Garrido/Reuters)

A Santa Claus puppet holding a Christmas tree is pictured against the sun in Berlin November 23, 2014. (Photo by Hannibal Hanschke/Reuters)

Revellers take part in the Children's Day parade of the Notting Hill Carnival in London, Britain, 28 August 2016. The street festival celebrates this year its 52nd anniversary and more than a million people are expected to attend on 28 and 29 August. (Photo by Will Oliver/EPA)

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)