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

The Boeoegg, a giant symbolic snowman made of wadding and and filled with firecrackers burns on top of a bonfire in Sechselaeuten square on April 24, 2017 in Zurich. When the bells of the Saint Peter's church chime six o'clock, the bonfire under the snowman is set in fire and the guildsmen wearing historical costumes ride around the bonfire. The faster the head of the snowman explods the warmer and more beautiful the summer will be. (Photo by Michael Buholzer/AFP Photo)

The “EMIEW3” robot (R) demonstrates communicating with a visitor during a press preview in Tokyo on April 8, 2016. Japanese electronics giant Hitachi unveiled its humanoid customer service and guidance robot “EMIEW3” and “remote brain” robotics IT platform. (Photo by Toshifumi Kitamura/AFP Photo)

Hotel staff practice self-defence skills after a training session given by team member of Special Weapons and Tactics (SWAT) team, in Hangzhou, Zhejiang province, April 7, 2016. (Photo by Reuters/Stringer)

South Sudanese wrestlers take part in a wrestling match for peace in Juba on April 19, 2016. The last wrestling match for peace was held in Juba the day before civil war broke out in December 2013. (Photo by Carl de Souza/AFP Photo)

Joshua Patino stands on a ladder to put finishing touches on a giant dinosaur exhibit at PAX East in the Boston Convention and Expo Center, Thursday, April 21, 2016, in Boston. PAX East, an annual celebration of gaming culture, is expected to draw tens of thousands of visitors Friday through Sunday. It's a place where serious gamers can preview unreleased video games and devices, compete in tournaments, hear live music and meet others for whom gaming is a way of life. (Photo by Elise Amendola/AP Photo)

Taiwanese-US artist Chin Chih Yang poses for a photograph with 30,000 aluminum cans after his performance called “Kill Me or Change” in Taipei, Taiwan, 23 April 2016. “Kill Me or Change!” is a performance piece that aims to raise awareness of the benefits of recycling and, encourage people to recycle to conserve resources. (Photo by Ritchie B. Tongo/EPA)

Models display a creation by K-Lynn Lingerie during a fashion show in the Lebanese capital Beirut on April 24, 2016. (Photo by Anwar Amro/AFP Photo)