A woman smokes marijuana during the annual 4/20 marijuana rally on Parliament Hill in Ottawa, Ontario, Canada, April 20, 2017. (Photo by Chris Wattie/Reuters)

A woman doing yoga at a fountain, in downtown Stuttgart, Germany, Thursday, June 22, 2017. Weather forecasts predict hot summer weather as well as thunderstorms for some parts of Germany. (Photo by Marijan Murat/DPA via AP Photo)

Cara Delevingne and Kate Moss attend the Burberry Prorsum show during London Fashion Week Spring Summer 2015 on September 15, 2014 in London, England. (Photo by Anthony Harvey/Getty Images)

A participant poses with his laptop during the 33rd Chaos Communication Congress on its opening day on December 27, 2016 in Hamburg, Germany. The annual event is bringing together 12,000 computer hackers and activists who will meet over the next four days to share expertise and discuss topics related to the society and the digital world. (Photo by Morris MacMatzen/Getty Images)

Anne Owen and Abigail Owen-Pontez strap into “Elee”, a car made of cutlery from American Airlines during the Everyones Art Car Parade May 14, 2005 in Houston, Texas. The silverware was purchased by Houston artist Mark Bradford when the airline had to convert to plasticware after the September 11, 2001 attacks on the World Trade Center and Pentagon. The parade includes around 280 cars and is part of Art Car Weekend along with a street festival, parade, carnival, ball and other events. (Photo by Dave Einsel/Getty Images)

Two sailors from HMS Fury enjoy a smoke with two women in bathing suits on a beach in Jersey, where their ship is on a visit. (Photo by William Vanderson/Fox Photos/Getty Images). 29th June 1935

A member of the Air Force's Wings of Blue Parachute Demonstration Team salutes as he jumps out of an aircraft, during the opening ceremony of Aviation Nation 2017 Nellis Air and Space Expo at Nellis Air Force Base, Nev., November 10, 2017. (Photo by Senior Airman Kevin Tanenbaum/Reuters/U.S. Air Force)

Former NBA player Yao Ming (R), a member of the 12th Chinese People's Political Consultative Conference (CPPCC) National Committee, is seen during an interview in Beijing, China, in this picture taken March 9, 2016. (Photo by Reuters/China Daily)