Free runners “3run” take advantage of O2's empty Slough HQ on the company's flexible working day on February 8, 2012 in Slough, England. (Photo by Ian Gavan/Getty Images for O2)

Punks gather in Blackpool for the annual Rebellion Punk Rock Festival on August 8, 2014 in Blackpool, England. This weekend a clash of musical cultures hits the famous seaside town as pogoing punks attending the annual Rebellion Festival at The Winter Gardens come shoulder to shoulder with traditional holidaymakers and seasiders. (Photo by Christopher Furlong/Getty Images)

A combination photo shows the faces of various attendees of New York Comic Con in Manhattan, New York, October 8, 2015. The event draws thousands of costumed fans, panels of pop culture luminaries and features a sprawling floor of vendors in a space equivalent to more than three football fields at the Jacob Javits Convention Center on Manhattan's West side. (Photo by Andrew Kelly/Reuters)

A tourist stands on the shore of a private beach in Naama Bay, Sharm el-Sheikh, south Sinai, Egypt, Sunday, November 8, 2015. Britain's foreign secretary says airport security in many cities will need to be overhauled if it is confirmed the Russian plane crash in the Sinai was caused by a bomb planted by the Islamic State group or someone inspired by the militants. (Photo by Vinciane Jacquet/AP Photo)

Participants of the 77th edition of the annual Christmas swimming 'Coupe de Noel' jump into the waters of Lake Geneva, in Geneva, Switzerland, 20 December 2015. More than 1,540 men and women braved the water temperature of just 8 degrees Celsius as they swam a 120 meters distance at the traditional Christmas swimming in Geneva. (Photo by Salvatore Di Nolfi/EPA)

Florin Bors, aged 8 from Bacau, northern Romania, wearing a bear fur takes a break from performing a holiday season ritual in Bucharest, Romania, Tuesday, December 16, 2014. In pre-Christian rural traditions, dancers wearing colored costumes or animal furs, touring house to house in villages singing and dancing to ward off evil. In recent years following the economic downturn in Romania, a European Union member since 2007, the tradition has moved to Romania's cities where dancers travel to perform the ritual for money. (Photo by Octav Ganea/AP Photo/Mediafax)

In this two photo combination picture, the Eiffel Tower with its usual lighting at left, and after the lighting was switched off at right, at the occasion of the Earth Hour, in Paris, France, Saturday March 28, 2015. This Saturday, 28 March 8:30 p.m. local time, individuals, businesses, cities and landmarks around the world are switching off their lights for one hour to focus attention on climate change. (Photo by Remy de la Mauviniere/AP Photo)

An Israeli boy swims next to sheep belonging to a Palestinian farmer in the West Bank village of Al-Auja in the Jordan Valley on April 8, 2015 during the Jewish Passover holiday. Thousands of Israelis spent the day outdoors, picnicking and touring the country during the eight-day Passover holiday, which commemorates the Israelites' exodus from Egypt some 3,500 years ago. (Photo by Menahem Kahana/AFP Photo)