Former U.S. Vice presidential candidate and Alaska Governor Sarah Palin (R) greets some of the thousands of motorcycle enthusiasts and military veterans participating in 'Rolling Thunder' rally May 29, 2011 in Arlington, Virginia. Although not an official guest, former U.S. Vice presidential candidate and Alaska governor Sarah Palin is expected to participate in today's motorcycle parade from the Pentagon to the National Mall.

Inductee Alice Cooper poses with a snake in the press room at the 26th annual Rock and Roll Hall of Fame Induction Ceremony at The Waldorf=Astoria on March 14, 2011 in New York City.

The sun catches on the panels of a 1928 Rolls Royce Phantom at Northington Grange, the summer home of the Grange Park Opera, on April 16, 2011 near Winchester, England. The English Heritage Grade 1 listed Greek Revival style property was the setting for the inter-war Rolls Royce20-Ghost Club members which was founded in 1949 by a group of owners of vintage Rolls Royce cars. (Photo by Matt Cardy/Getty Images)

“A robot suit that can help the elderly or disabled get around was given its global safety certificate in Japan on February 27, 2013, paving the way for its worldwide roll-out”. Photo: Robot suit “Hybrid Assistive Limb (HAL)” worn by a man developed by University of Tsukuba is seen lifting a 30kg weight during 2005 International Robot Exhibition on November 30, 2005 in Tokyo, Japan. By wearing the power suit, it makes it easier to move and lift heavy things. (Photo by Koichi Kamoshida)

Mechanics work in the Buggy belonging to Argentina's Manuel Sisterna and Adrian Echegaray during technical verification ahead of the Dakar Rally 2015 in Buenos Aires January 1, 2015. (Photo by Enrique Marcarian/Reuters)

A horse buggy is headed for the stables on a foggy night in New Orleans, Monday, December 18, 2017. (Photo by David Grunfeld/NOLA.com The Times-Picayune via AP Photo)

March 28, 1967. Egg Roll; A large bunny attracted the attention of children and their parents during the annual Easter egg roll Monday on the south lawn of the White House. The bunny was made by Fred Johansen, Silver Spring, Md. Nearly 17,000 youngsters and adults took part in the egg rolling. The President and Mrs. John-son were not at the festivities because they were in Camp David, Md. The tradition of egg rolling was begun in 1878 during the administration of Rutherford B. Hayes. (Photo by Minneapolis Star Tribune)