Voters line up to cast their ballots at a polling station in the city of Qom, Iran. Elections for Iran's parliament (Majlis) and Assembly of Experts kicked off on Friday, February 26, 2016. (Photo by Ahmad Halabisaz/Xinhua via ZUMA Wire)

A group of youngsters dressed as ghouls and zombies for Halloween parade in downtown Lisbon, Portugal, Friday, October 31, 2014. (Photo by Francisco Seco/AP Photo)

Tourists pose with pigeons in the flooded St. Mark's Square in Venice, on November 7, 2014. The high water, a combination of high tides and a strong Scirocco wind in the Adriatic Sea, stood at 110 centimeters early on November 7. The city has for years been wrestling with the problems posed by the threat of rising sea levels. (Photo by Olivier Morin/AFP Photo)

A handout picture provided by Solar Impulse on 18 March 2015 shows the Swiss solar-powered plane Solar Impulse 2, HB-SIB, taking off with Swiss explorer Andre Borshberg on board for the third leg Ahmedabad to Varanasi, of the Round-The-World, in Ahmedabad, India, 18 March 2015. Swiss explorers Bertrand Piccard and Andre Borschberg attempt to circumnavigate the world flying with an aircraft, with a 72 metres wingspan, powered only by solar energy without a drop of fuel. (Photo by EPA/Solar Impulse)

Green Bay Packers' Johnathan Calvin rides a bike to NFL football training camp on July 27, 2017, in Green Bay, Wis. (Photo by Morry Gash/AP Photo)

Bonbibi, Treehouse Point, Fall City, WA. The Bonbibi is balanced on two steel yokes. The yokes spread out the load and allow for tree growth and movement in the wind. A small deck hangs from the beams below and uses the treehouse itself to shelter guests. (Photo by Pete Nelson)

A man washes his horse as a woman bathes her son at concrete water pens under a flyover in a slum area in Kolkata, India October 21, 2016. (Photo by Rupak De Chowdhuri/Reuters)

Nursing and care personnel lay on the floor in the ICU unit, during a demonstration on International Nursing and Care day, at the Mont Legia Hospital in Liege, Belgium, Wednesday, May 12, 2021. Hospital personnel around Belgium took part in various actions around the country on Wednesday to highlight the work they do and demand better recognition. (Photo by Valentin Bianchi/AP Photo)