Members of the Royal Navy respond to a simulated fire in a Vanguard-class submarine control room training facility at Clyde naval base in Faslane, Scotland on January 21, 2016. (Photo by Photograph: Danny Lawson/PA Wire)

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)

Li Yuming, a local farmer who is interested in scientific invention, works on his unfinished miniature submarine “Xiaguang V” on the outskirts of Wuhan, capital of central China's Hubei province August 24, 2007. “Xiaguang V”, which is 3-metre long, 1.2-metre in height, has a maximum diving depth of 20 metres, and can hold two adults and one child at the same time. The submarine will be used for tour after safety test, local media said. (Photo by Reuters/Stringer)

Zhao Qiang walks across a street in Shenyang, Liaoning province, April 14, 2014. Zhao, a community officer of the China Disabled Persons' Federation, was diagnosed with multiple when he was two, with the resulting tumour affecting the growth of his left leg, his grandmother told local media, citing a doctor's diagnosis. His uncle modified his shoes, fitting them with stools, to allow Zhao to stand and walk. (Photo by Reuters/Stringer)

A country music fan cools off in the wind on the second day of the Stagecoach country music festival in Indio, California April 26, 2014. (Photo by Mike Blake/Reuters)

An injured national guard officer is carried away by comrades outside the parliament building in Kiev, Ukraine, August 31, 2015. Nearly 90 people were wounded and several of them were in a serious condition on Monday after several explosive devices were thrown from crowds in front of the Ukrainian parliament building in Kiev, the interior minister said in a Tweet. (Photo by Valentyn Ogirenko/Reuters)

In this February 26, 1962 file photo, Mercury astronaut John Glenn, and his wife, Annie, ride in the back of an open car with Vice-President Johnson during a parade in Glenn's honor in Washington. The Capitol is seen in the background. Glenn, the first American to orbit Earth who later spent 24 years representing Ohio in the Senate, died Thursday, Dec. 8, 2016, at the age of 95. (Photo by AP Photo)