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)

Employees of a food stand take pictures of Titan, a robot created by England Cyberstein Robots, performing at the Danilovsly market in downtown of Moscow, Russia, 12 May 2014. Titan visited to Moscow to attend “Bal Robotov”, an interactive exhibition of the most recent advances in robotics which will be opened on 15 May in Artplay Moscow exhibition center. Titan worked alongside superstars including Will.i.am, Rihanna, Will Smith and Jackie Chan. (Photo by Sergei Ilnitsky/EPA)

A woman browses through kimonos for sale at Boroichi flea market in Tokyo December 15, 2014. In the 16th century, Boroichi was a place for farmers to buy and sell rags, known as boro, for mending clothes and weaving sandals. Now in its 436th year, the original spirit lingers, with about 700 stands hawking fabric, used clothes and piles of rags. Others sell kitchen tools, pottery, seaweed and spices. About 200,000 people flock to the market, which is only open for four mid-winter days a year – two in December and two in January. (Photo by Thomas Peter/Reuters)

Soldiers stand in front of a floral decoration during celebrations to commemorate the 70th anniversary of the establishment of the Vietnam People's Army at the National Convention Center in Hanoi December 20, 2014. The Vietnam People's Army was founded on December 22, 1944 and led by General Vo Nguyen Giap in Cao Bang province, initially with only 34 members. (Photo by Reuters/Kham)

Men stand at the top of a traffic lights post as they attend a rally to protest against satirical cartoons of prophet Mohammad, in Grozny, Chechnya January 19, 2015. Tens of thousands of people staged the rally on Monday in Chechnya against French magazine Charlie Hebdo's cartoons of the prophet, which the predominantly Muslim region's leader denounced as “vulgar and immoral”. The posters read, “Mohammad”. (Photo by Eduard Korniyenko/Reuters)

A man stands next to the body of a migrant child washed up on a beach in Canakkale's Bademli district on January 30, 2016 after at least 37 migrants drowned when their boat sank in the Aegean Sea while trying to cross from Turkey to Greece, Turkey's state-run Anatolia news agency reported. The migrants, who included those from Myanmar, Afghanistan and Syria, set sail from the Canakkale province to reach the nearby Greek island of Lesbos, Anatolia said. (Photo by Ozan Kose/AFP Photo)

A member of security personnel stands on duty on an empty train platform inside a station on the Subway Line Number 1 on the eve of the Chinese Lunar New Year, in Beijing, China, February 7, 2016. According to local media, traffic in Beijing has seen a rare relief from its usual heavy pressure after 15 million people have left the city, heading for family reunions in their hometowns on the eve of the Chinese Lunar New Year of Monkey. (Photo by Jason Lee/Reuters)

A boy carries a dog as he stands after a Peruvian police operation to destroy illegal gold mining camps in a zone known as Mega 14, in the southern Amazon region of Madre de Dios July 14, 2015. Peruvian police razed dozens of illegal gold mining camps at the edge of an Amazonian nature reserve this week, part of a renewed bid to halt the spread of wildcatting in a remote rainforest region. (Photo by Janine Costa/Reuters)