The Boeoegg, a giant symbolic snowman made of wadding and and filled with firecrackers burns on top of a bonfire in Sechselaeuten square on April 24, 2017 in Zurich. When the bells of the Saint Peter's church chime six o'clock, the bonfire under the snowman is set in fire and the guildsmen wearing historical costumes ride around the bonfire. The faster the head of the snowman explods the warmer and more beautiful the summer will be. (Photo by Michael Buholzer/AFP Photo)

A riot policeman watches as a police vehicle burns in Braamfontein, Johannesburg, South Africa, Tuesday, October 25, 2016. Rioters in South Africa set a police vehicle on fire Tuesday and stoned vehicles near a Johannesburg university that has been the scene of sometimes violent protests by students demanding free education. The violence broke out in streets near the University of the Witwatersrand at around the same time that student protesters met and marched off the campus, South African media reported. (Photo by Yeshiel Panchia/AP Photo)

In this October 21, 2015, file photo, a young man rides a hoverboard along a Manhattan street toward the Empire State Building in New York. More than 500,000 hoverboards are being recalled after reports that they can burst into flames. The Consumer Product Safety Commission said Wednesday, July 6, 2016, it has received 99 reports of battery packs in the two-wheel motorized scooters catching fire or exploding that causing burns or property damage. The recalled hoverboards were made by eight companies. (Photo by Kathy Willens/AP Photo)

In this photo taken on Saturday, March 9, 2019, a visitor dances in front of a sculpture burning at the Maslenitsa (Shrovetide) festival at the Nikola-Lenivets art park in Nikola-Lenivets village, about 200 kilometers (125 miles) south-west of Moscow, Russia. As part of the celebrations of Maslenitsa (Shrovetide) Holiday in Russian, a folk holiday which heralds the beginning of spring, contemporary artist and park founder Nikolay Polissky built a giant sculpture made of wood and hay which was burnt to ashes during a traditional bonfire. (Photo by Alexander Zemlianichenko Jr./AP Photo)

A protester throws a stone towards a burning police bus in front of him, during clashes with police, in central Kiev, Ukraine, Sunday, January 19, 2014. Hundreds of protesters on Sunday clashed with riot police in the center of the Ukrainian capital, after the passage of harsh anti-protest legislation last week seen as part of attempts to quash anti-government demonstrations. The violent scenes further escalated this ex-Soviet republic's political crisis and showed a rift among opposition leaders, one of whom fought bravely to stop the violence, while others condemned the events from afar. (Photo by Evgeny Feldman/AP Photo)

Members of the 2013 “Jarl Squad” take part in the annual Up Helly Aa festival which culminates in the burning of a Viking Galley in Lerwick, Shetland Islands on January 29, 2013. Up Helly Aa celebrates the influence of the Scandinavian Vikings in the Shetland Islands and has employed this theme in the festival since 1870. The event culminates with up to 1,000 “guizers” (men in costume) throwing flaming torches into their Viking longboat. (Photo by Andy Buchanan/AFP Photo)

A masked Burundian protester faces soldiers in front of a burning barricade during an anti-government demonstration against President Pierre Nkurunziza's bid for a third term in the capital Bujumbura, Burundi, 25 May 2015. Street protests continued on 25 May as the United Nations Secretary-General Ban Ki-moon condemned the killing of the leader of the oppsition party Union for Peace and Development (UPD) Zedi Feruzi who opposed Nkurunziza's bid. (Photo by Dai Kurokawa/EPA)