A girl attends Friday prayers in front of an army tank in Tahrir Square in Cairo February 18, 2011. Five years ago thousands of protesters took to the streets demanding the end of the 30-year reign of President Mubarak as Egypt became the second country to join the Arab Spring. After weeks of clashes, strikes and protests across Egypt, Mubarak resigned on February 11, 2011. (Photo by Suhaib Salem/Reuters)

Pilot Akmal Bin Abdul Kahar watches South Korea's Black Eagles aerobatics team perform a manoeuvre during an aerial display at the Singapore Airshow at Changi Exhibition Center February 18, 2016. (Photo by Edgar Su/Reuters)

A garbage collector, with his horse and cart, prepares to unload rubbish at the municipal dump in Nezahualcoyotl, on the outskirts of Mexico City, February 18, 2015. Hundreds of horse or donkey-drawn carts will disappear from the streets of a municipality in the state of Mexico, located on the outskirts of Mexico City, and will be replaced by motorized vehicles, local authorities said. (Photo by Henry Romero/Reuters)

Some women doing yoga pose on the hammocks during the Anti-Gravity yoga class at Svarga e-Motion Sanctuary at Dharmawangsa Square, Jakarta, Saturday, April 18, 2015. Anti-Gravity Yoga or “aerial yoga”, is a new type of yoga, originating in New York but now being practised in several countries, which combines the traditional yoga poses, pilates and dance with the use of a hammock. (Photo by Jurnasyanto Sukarno/JG Photo)

Images created with Post-it notes are seen in the windows of offices at 75 Varick Street in lower Manhattan, New York, U.S., May 18, 2016, where advertising agencies and other companies have started what is being called a “Post-it note art war” with employees creating colorful images in their windows with Post-it notes. (Photo by Mike Segar/Reuters)

Dancers wearing new bikinis perform in front of passers-by and a line of photographers during a promotional flash mob event on a square outside Shinjuku station in Tokyo on July 18, 2016. The event was organized by the Japan Swimsuit Association to promote new swimwear. (Photo by Toru Yamanaka/AFP Photo)

Ryan Randall plays the bagpipes outside a polling station in Edinburgh, Scotland September 18, 2014. Polling in the referendum on Scottish independence began on Thursday morning, as Scotland votes whether or not to end the 307-year-old union with the rest of the United Kingdom. (Photo by Paul Hackett/Reuters)

Sgt. William Olas Bee, a U.S. Marine from the 24th Marine Expeditionary Unit, has a close call after Taliban fighters opened fire near Garmsir in Helmand Province of Afghanistan, May 18, 2008. (Photo by Goran Tomasevic/Reuters)