Robot couple Xiaolan (L) and Xiaotao carry trays of food at a restaurant in Jinhua, Zhejiang province, China, May 18, 2015. The restaurant, which opened on Monday, has two robots delivering food for customers. The robots were designed as a couple, Xiaolan and Xiaotao, according to local media. (Photo by Reuters/Stringer)

Yuri Gagarin does not always show up in full-scale astronautics. In this picture he smiles during his summer vacation in Sochi, Russia in 1961 with sunglasses and sunhat in the camera. (Photo by Imago/Eastnews)

A visitor jumps for a photograph on the world's highest and longest glass-bottomed bridge above a valley in Zhangjiajie in China's Hunan Province on August 21, 2016. The bridge, which opened to the public on a trial basis on Saturday, spans 430 meters (1,410 feet) and rises about 300 meters (984 feet) above a valley in a scenic zone, making it the world's highest and longest glass-bottomed bridge according to Chinese state media. (Photo by Fred Dufour/AFP Photo)

A home-made steam train, designed by Pavel Chilin, rides on a make-shift railway across country house neighborhood in the settlement of Ulyanovka in Leningrad region, Russia on November 4, 2019. (Photo by Anton Vaganov/Reuters)

A demonstrator is detained by riot police during a protest, in La Paz, Bolivia on November 21, 2019. Bolivia's interim President Jeanine Anez asked Congress Wednesday to approve a law that would allow for new elections, after deadly unrest following the resignation of Evo Morales and the disputed October 20 ballot. (Photo by Marco Bello/Reuters)

A Sotheby's employee poses with a “Return of the Jedi” promotional C-3PO Helmet 1983, estimated at £15,000-£25,000 created by George Lucas' visual effects company during a photocall at Sotheby's in London, Britain on December 6, 2019. (Photo by Thomas Mukoya/Reuters)

A Iranian man walks with a sheep he bought at a market in the capital Tehran on September 12, 2016, as Muslims mark the first day of the Eid al-Adha (Feast of the Sacrifice) holiday. Muslims across the world celebrate the annual festival of Eid al-Adha, or the festival of sacrifice, which marks the end of the Hajj pilgrimage to Mecca and commemorates prophet Abraham's readiness to sacrifice his son to show obedience to God. (Photo by AFP Photo/Stringer)

A demonstrator jumps from a vehicle of the Organisation for Security and Co-operation in Europe (OSCE) during a protest to demand what protesters say is true information from the OSCE about the shelling in Donetsk, Ukraine (since April 2014, the city is the administrative centre of the Donetsk People's Republic), July 23, 2015. The graffiti reads, “Stop moronic war!”. (Photo by Alexander Ermochenko/Reuters)