A Police officer checks a man wearing a carnival costume in Venice, Italy, Sunday, January 31, 2016. Carnival-goers in Venice are being asked by police to momentarily lift their masks as part of new anti-terrorism measures for the annual festivities. Police are also examining backpacks and bags and using metal-detecting wands before revelers are allowed into St. Mark's Square, the heart of the Venetian carnival. (Photo by Luigi Costantini/AP Photo)

A U.S. Army soldier with the 10th Special Forces Group and his military working dog jump off the ramp of a CH-47 Chinook helicopter from the 160th Special Operations Aviation Regiment during water training over the Gulf of Mexico as part of exercise Emerald Warrior 2011 on March 1, 2011. (Photo by Tech. Sgt. Manuel J. Martinez/U.S. Air Force)

African women in their grandmothers' clothes: Joana Choumali’s portraits show modern African women swapping jeans for kente cloth – and diving into the dazzling cultural heritage of their families. (Photo by Joana Choumali/The Guardian)

Couple getting intimate on couch. (Photo by Vincent Besnault/Getty Images)

A woman dressed in an alien space suit carries an American flag and a sign that reads “Women's Revolution 1971” as she marches in a Women's Liberation demonstration on Fifth Avenue in New York, August 26, 1971. (Photo by Marty Lederhandler/AP Photo)

A veterinarian kisses an 8-month-old cat, wearing a prosthetic two-wheel device, at a veterinary hospital in Chongqing municipality, March 16, 2015. The cat's rear legs lost the abilty to walk after falling from the ninth to fifth floor of a building last November, its since undergone four major surgeries which included removing parts of its organs, local media reported. (Photo by Reuters/China Daily)

A robot Ecce by the Robot studio is pictured at the world's largest industrial technology fair, the Hannover Messe, in Hanover April 13, 2015. (Photo by Wolfgang Rattay/Reuters)

Indonesian tourists take photos at the Marina Bay in Singapore May 14, 2015. When Singapore celebrated its 50th birthday as an independent country in August,the city state bore little resemblance to the tiny island nation that was expelled from Malaysia in 1965. Its physical stature has swollen by 20 percent thanks to one of the world's most aggressive land reclamation drives. (Photo by Edgar Su/Reuters)