Tomomi Ota pushes a trolley loaded with her humanoid robot Pepper as she crosses a street in Omotesando shopping district in Tokyo, Japan, 24 March 2016. Telecommunications and mobile phone carrier SoftBank Corp. opened a robot-staffed store where 10 Pepper humanoid robots welcome customers looking to buy a mobile phone. The store will be opened until 30 March 2016. (Photo by Franck Robichon/EPA)

Businesswoman and vendor Sonia Maria Paypay sells clothing at a stand at the commercial zone of Gamarra in Lima, April 16, 2015. (Photo by Mariana Bazo/Reuters)

A young visitor interacts with a baby hippopotamus swimming in its enclosure at the Berlin Zoo on January 1, 2018. Tourists and locals flocked to the zoo in the German capital on the unseasonably warm first day of the year. (Photo by Odd Andersen/AFP Photo)

Completion is near on Monaco's tallest skyscraper ever, and its first new one since the 1980s. Fueled by a luxury-housing boom in the tax-haven nation, the Odeon Tower's so-called Sky Penthouse is expected to sell for more than any other apartment in the world has ever sold before. Photo: The five-story Sky Penthouse is expected to be complete in September 2015. The water slide extends from a dance floor in the residence down to a private infinity pool. (Photo by Tour Odeon)

Community members look for the nameplates of their loved ones Tuesday, December 9, 2014 at Myers Funeral Service and Crematory in Porterville, Calif. during the 20th year of the memorial tree lighting. (Photo by Chieko Hara/AP Photo/The Porterville Recorder)

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)

A serviceman walks near an APC while a helicopter flies on the position of the Ukrainian troops in Donetsk region on August 9, 2014. Fighting with pro-Russian separatists in eastern Ukraine has left 13 troops dead in the last 24 hours, Ukraine's military said Saturday. (Photo by Anatolii Stepanov/AFP Photo)

Robert The Bruce's army from The Clanranald Trust during a rehearsal for the Battle of Bannockburn re-enactment performance which will be staged at the Bannockburn Live Event in Bannockburn, the 700th anniversary of the battle, on June 27, 2014. (Photo by Andrew Milligan/PA Wire)