The Queen Elizabeth Tower (Big Ben) is reflected in a puddle as a cyclist rides by in London, on 27 June 2016. Britain began preparations to leave the European Union on Monday but said it would not be rushed into a quick exit, as markets plunged in the wake of a seismic referendum despite attempts to calm jitters. (Photo by Leon Neal/AFP Photo)

Visitors review their cell phone photos of an installation called “Plexus A1” by artist Gabriel Dawe, one of nine large-scale art installations displayed at the “Wonders” exhibit at the Renwick Art Gallery in Washington, DC, Wednesday, January 13, 2016. Built in the 1860s, the Renwick was the first American building to be designed specifically as an art museum; it recently reopened after a two year renovation. (Photo by Jim Lo Scalzo/EPA)

A Palestinian youth demonstrates his parkour skills on a street in Gaza City, January 15, 2016. (Photo by Suhaib Salem/Reuters)

Rich Paul, Simon, Tristan Thompson, Khloe Kardashian, Lucas Newton, Kendall Jenner, Justine Skye, Jordan Woods and Kylie Jenner pose for a photo as Remy Martin celebrates Tristan Thompson's Birthday at Beauty in Los Angeles on March 1, 2018. (Photo by Jerritt ClarkJerritt Clark/Getty Images for Remy Martin)

An employee of a bakery talks on his mobile while balancing on his head a tray of freshly baked bread from a local bakery in a street in Cairo, Egypt, January 12, 2016. (Photo by Asmaa Waguih/Reuters)

Participants climb over a wall at the “Tough Mudder” endurance event series in Arnsberg September 6, 2014. Competitors who took part in the endurance event saw themselves having to overcome various military style obstacles. (Photo by Ina Fassbender/Reuters)

Libyan leader Muammar Gaddafi attends the inauguration ceremony of Jacob Zuma on May 9, 2009 in Pretoria, South Africa. Jacob Gedleyihlekisa Zuma is South Africa's fourth President since the end of apartheid. (Photo by Foto24/Gallo Images/Getty Images)