Robert The Bruce's army from The Clanranald Trust during a rehearsal for the Battle of Bannockburn re-enactment performance which will be staged at the Bannockburn Live Event in Bannockburn, the 700th anniversary of the battle, on June 27, 2014. (Photo by Andrew Milligan/PA Wire)

A woman spends her time outdoors to observe the ancient festival of Sizdeh Bedar, an annual public picnic day on the 13th day of the Iranian new year, at the Tochal mountainous area northern Tehran, Iran, Sunday, April, 2, 2017. Sizdeh Bedar, which comes from the Farsi words for “thirteen” and “day out”, is a legacy from Iran's pre-Islamic past that hard-liners in the Islamic Republic never managed to erase from calendars. (Photo by Ebrahim Noroozi/AP Photo)

Revelers dance at the Old Settler's Music Festival in Driftwood, Texas, U.S. on April 22, 2017. (Photo by Mohammad Khursheed/Reuters)

Starlings are seen at their nesting box in a private garden in the town of Bobruisk, Belarus, April 8, 2018. (Photo by Vasily Fedosenko/Reuters)

North Korean leader Kim Jong Un, his wife Ri Sol Ju and Song Tao, head of the International Department of Communist Party of China (CPC) Central Committee, applaud with ballet dancers in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang April 17, 2018. (Photo by Reuters/KCNA)

Iraqi firefighters try to stop the fire of burning oil wells in Kirkuk, northern Iraq, 02 June 2016. Two Khabbaz oil field wells in Kirkuk Province, northern Iraq, exploded by suspected insurgents, a security official said. (Photo by EPA/Stringer)

Angel Hall, 22, (C) and Bri Artis, 21, (R) dance in a silent disco on the fourth and final day of the Firefly Music Festival in Dover, Delaware on June 17, 2018. (Photo by Mark Makela/Reuters)

A handout photo made available by Limex Images of Pete McLeod of Canada (R) and Kirby Chambliss of the United States flying over the city of Kazan prior to the fifth stage of the Red Bull Air Race World Championship in Russia on August 22, 2018. (Photo by Joerg Mitter/EPA/EFE/Limex Images)