A man salts a downtown sidewalk in Washington, Thursday, March 5, 2015, as snow begins to fall. The U.S. federal government said its offices in the Washington area will be closed Thursday because of a new round of winter weather expected in the region. The Office of Personnel Management said non-emergency personnel in and around Washington were granted excused absences for the day. Emergency employees and telework-ready employees were expected to work. (AP Photo/Andrew Harnik)

A woman takes cover as shots are fired by police officers as they face off with stone-throwing protesters, during an anti-government demonstration in Bujumbura, Burundi, 20 May 2015. Police officers fired shots and teargas canisters in running battles with protesters who demonstrated against Burundi's President Pierre Nkurunziza's bid for a third term. Presidential spokesman man said on 20 May that the country will postpone its parliamentary and local council elections, previously scheduled for 26 May, to 05 June 2015. According to the United Nations' refugee agency, more than 105,000 Burndians have fled the country to seek refuge in neighbouring countries such as Rwanda, DR Congo, and Tanzania. (Photo by Dai Kurokawa/EPA)

In a photo taken on June 5, 2017 a traffic security officer stands on duty at an intersection in Pyongyang. Officially known as traffic security officers but universally referred to as traffic ladies, they are chosen for their looks in a society that remains traditionalist in many respects. They must leave the role if they marry, and have a finite shelf-life, with compulsory retirement looming at just 26. (Photo by Ed Jones/AFP Photo)

A giant Rubber Duck created by Dutch artist Florentijn Hofman is towed along Hong Kong's Victoria Habour Thursday, May 2, 2013. Since 2007 the 16.5-meter (54 feet)-tall Rubber Duck has traveled to various cites including Osaka, Sydney, Sao Paulo and Amsterdam. (Photo by Vincent Yu/AP Photo)

Senator Barack Obama (D-IL) (R) stands in front of Senator Hillary Clinton (D-NY) as they arrive for U.S. President George W. Bush's annual State of the Union speech to a joint session of Congress at the U.S. Capitol in Washington in this January 23, 2007 file photo. Hillary Clinton announced her second run for the presidency on April 12, 2015 starting her campaign as the Democrats' best hope of fending off a crowded field of lesser-known Republican rivals and retaining the White House. (Photo by Larry Downing/Reuters)

A humanoid robot named Kansei, meaning “sensibility” in Japanese, makes a facial expression depicting “happiness”, next to the word “Love” during a demonstration at a laboratory of Meiji University's Robot and Science Institute in Kawasaki, south of Tokyo in this June 4, 2007 file photo. Three-fourths of robot installations over the next decade are expected to be concentrated in four areas: transportation equipment, including the automotive sector; computer and electronic products; electrical equipment and machinery. Labor costs have climbed in countries such as China that have been popular for outsourcing production, while technological advances for robots allow them to be more flexible and perform more tasks. (Photo by Yuriko Nakao/Reuters)

"Steve McCurry: India", co-organized by the Rubin Museum and the International Center of Photography, brings together photographs of India-its people, monuments, landscapes, seasons, and cities. The exhibition at the Rubin Museum in New York runs from November 18, 2015 – April 4, 2016. Here: A boy in mid-flight in Jodhpur, Rajasthan, India, in 2007. (Photo by Steve McCurry)

An Airbus A380 aircraft prepares to land at Mumbai airport in this May 8, 2007 file photo. Sentiment at some of Asia's biggest firms deteriorated again in the fourth quarter, falling to a four-year low under the weight of concerns about slowing growth in China, the region's biggest economy, a Thomson Reuters/INSEAD survey showed. (Photo by Arko Datta/Reuters)