Lioness and hyena posture to one another, in Masai Mara, Kenya, August 2015. A photographer captured one of the oldest rivalries in the animal kingdom as a pair of lions went head to head with a pack of hungry hyenas. (Photo by Ingo Gerlach/Barcroft Images)

A visitor kneels down nex to an iCub robot made by the Italian Institute of Technology at the scientists congress IROS 2015 in Hamburg, Germany October 2, 2015. The robot congress is organized by TAMS group (Technical Aspects of Multimodal Systems) of Hamburg's university. (Photo by Fabian Bimmer/Reuters)

A man steers with his legs while riding a motorcycle on a road in Vietnam's northern Hoa Binh province, outside Hanoi, October 15, 2015. (Photo by Reuters/Kham)

Gurung girls wearing traditional costumes dance while taking part in a New Year parade in Kathmandu, Nepal December 30, 2015. Members of the Gurung community in Nepal celebrate their Tamu Lhosar or Losar (New Year) with a feast and various cultural programs to usher in the year of the Monkey. (Photo by Navesh Chitrakar/Reuters)

A fireman pulls a woman and her dog to shore, by a row of houseboats on the river Seine in Paris France, Wednesday June 1, 2016. The Seine River has overflowed embankments in Paris as floods hit or threaten cities and towns around France. (Photo by Jerome Delay/AP Photo)

Just Dance 2017 performance at Ubisoft E3 2016 – Day 2 at the Los Angeles Convention Center on Tuesday, June 14, 2016, in Los Angeles. (Photo by Dan Steinberg/Invision for Ubisoft/AP Images)

Women perform yoga on a dried river bank in Yunyang county, Chongqing Municipality, August 21, 2016. (Photo by Reuters/China Daily)

A woman affected by tear gas is assisted during a May Day protest against austerity measures, in San Juan, Puerto Rico May 1, 2018. (Photo by Alvin Baez/Reuters)