Villagers look on as Mount Sinabung volcano spews thick volcanic ash, as seen from Beganding village in Karo, North Sumatra province, on May 19, 2017. Sinabung roared back to life in 2010 for the first time in 400 years. After another period of inactivity, it erupted once more in 2013 and has remained highly active since. (Photo by Ivan Damanik/AFP Photo)

A participant smiles at the annual Christopher Street Day parade on Kurfuerstendamm in Berlin, Germany, June 27, 2015. (Photo by Fabrizio Bensch/Reuters)

Members of the Royal Navy respond to a simulated fire in a Vanguard-class submarine control room training facility at Clyde naval base in Faslane, Scotland on January 21, 2016. (Photo by Photograph: Danny Lawson/PA Wire)

A pilot inflates a hot air balloon while taking part in the 38th International Balloon Festival of Chateau-d'oex, Switzerland, 23 January 2016. The festival takes place from 23 to 31 January. (Photo by Vincent Vannay/EPA)

A woman aims a World War II machine gun at a military show during celebration of the Defenders of the Fatherland Day in St.Petersburg, Russia, Tuesday, February 23, 2016. The day, celebrated in Russia on February 23, honors the nation's military and is a nationwide holiday. (Photo by Dmitri Lovetsky/AP Photo)

Palestinian woman Jihan Abu Muhsen prepares her donkey with her son Kareem before going work collecting bricks for sale from sites of demolished buildings, at her dwelling in Khan Younis in the southern Gaza Strip March 8, 2016. Abu Muhsen gathers bricks from the sites of demolished buildings and sells them to recycling factories. She earns around 20 shekels ($5) a day and her 10-year-old son Mohammad helps her when he is not at school. (Photo by Ibraheem Abu Mustafa/Reuters)

A tourist stands on a paddle boat near soldiers taking part on a military and police drill in preparation for the temporary closure of the holiday island Boracay in Philippines on April 24, 2018. (Photo by Erik De Castro/Reuters)

Students from St Andrews University are covered in foam as they take part in the traditional Raisin Weekend in the Lower College Lawn, at St Andrews in Scotland on October 22, 2018. The “raisin weekend” stems from a gift of raisins (now flour and foam) traditionally given by a first year student to their academic “parents” in gratitude for their guidance. (Photo by Russell Cheyne/Reuters)