Participants descend a hill in home- made vehicles during the 29 th Car Festival in Medellin, Antioquia department, Colombia, on November 18, 2018. (Photo by Joaquin Sarmiento/AFP Photo)

Eagle Prime (MK3), a giant robot by MegaBots Inc. which manufactures giant piloted humanoid fighting robots headquartered in Berkeley, California on October 18, 2017. (Photo by Courtesy Michael Mauldin/Reuters/MegaBots Inc)

A mahout guards the elephants during the annual Vrischikolsavam festival, which features a colourful procession of decorated elephants along with drum concerts, at a temple in Kochi, India, November 18, 2017. (Photo by Sivaram V/Reuters)

A person waits outside fashion show of designer Marina Hoermanseder at the Berlin Fashion Week Autumn/Winter 2018 in Berlin, Germany, January 18, 2018. (Photo by Hannibal Hanschke/Reuters)

A fuel cell electric vehicle (FCEV) by Nissan is shown at China (Guangzhou) International Automobile Exhibition in Guangzhou, China November 18, 2016. (Photo by Bobby Yip/Reuters)

A woman walks past a caricature of Britain's Foreign Secretary Boris Johnson in east London, Britain November 18, 2016. (Photo by Andrew Winning/Reuters)

Salvadoran clown Cosquilla poses for a picture during the VIII Central America Clown Convention in San Salvador, El Salvador, May 18, 2016. (Photo by Jose Cabezas/Reuters)

F/A-18 fighter jet takes off from the USS Harry S. Truman aircraft carrier in the eastern Mediterranean Sea June 13, 2016. (Photo by Baz Ratner/Reuters)