Selfie picture shows Swiss pioneer Bertrand Piccard during the last leg of the round the world trip with Solar Impulse 2 over the Arab peninsula July 25, 2016. (Photo by Jean Revillard/Bertrand Piccard/Reuters/SI2)

Two robotic legged squad support system (LS3) machines by the Defense Advanced Research Project Agency follow a technician during a demonstration at Joint Base Myer-Henderson Hall, Virginia, on September 10, 2012. (U.S. Marine Corps photo by Sgt. Mallory S. VanderSchans via The Atlantic)

In this July 15, 2015 photo, Nepalese amputee victims Khendo Tamang, left, and Nirmala Pariyar, both 8, share a single pair of shoes at the Bir Trauma Center in Kathmandu, Nepal. After suffering serious leg wounds in Nepal's massive 2015 earthquake that killed and injured thousands, both girls were brought to the Bir Trauma Center in Kathmandu, to receive single leg amputations. Following their surgeries, Nirmala's relentless cheerfulness drew a still very depressed Khendo close and both found an inseparable friendship which has helped their emotional wounds heal. (Photo by Niranjan Shrestha/AP Photo)

A member of the “Avocadoo” club performs a pole dance on a street sign pole in Lodz, central Poland on June 27, 2013. Talk about a traffic stopper: three pole dancers in central Poland have been honing their skills out in the streets, throwing their legs around signposts to the surprise and delight of many a passerby. (Photo by Janek Skarzynski/AFP Photo)

A boy holds his mother's leg as he cries in front of their damaged house after a strong 6.6 magnitude earthquake at Longmen village, Lushan county in Ya'an, Sichuan province. (Photo by Jason Lee/Reuters)

A boy rides on a snow wagon towed by a robot dressed as a Teddy bear, which only moves forward by moving its legs, during the Ice and snow carnival at Taoranting park in Beijing February 9, 2015. (Photo by Kim Kyung-Hoon/Reuters)

Salzburg's Patson Daka celebrates after scoring during the Europa League round of 32 second leg soccer match between FC Salzburg and Club Brugge at the Arena in Salzburg, Austria, Thursday, February 21, 2019. (Photo by Leonhard Foeger/Reuters)

Double amputee dog Cora Rose balances on her hind legs to watch Zach Skow repairing her cart on a street in Washington, U.S., May 15, 2019. Cora Rose serves in a prisoner therapy program founded by Skow called “Pawsitive Change” in California. (Photo by Kevin Lamarque/Reuters)