People dressed as zombies take part in a “Zombie Walk” parade in Athens, Greece, February 25, 2017. (Photo by Michalis Karagiannis/Reuters)

Hospitality staff members laugh as they stand on Tiananmen Square before the closing ceremony of China's 19th Party Congress at the Great Hall of the People in Beijing, Tuesday, October 24, 2017. The ruling Communist Party on Tuesday formally lifted Xi Jinping's status to China's most powerful ruler in decades, setting the stage for the authoritarian leader to tighten his grip over the country while pursuing an increasingly muscular foreign policy and military expansion. (Photo by Mark Schiefelbein/AP Photo)

In this photo provided by Tasnim News Agency, relatives weep over the body of an earthquake victim, in Sarpol-e-Zahab, western Iran, Monday, November 13, 2017. An earthquake measuring 7.3 on the Richter scale rocked northern Iraq and Iran, the U.S. Geological Survey said on Sunday evening. Photo by Farzad Menati/Tasnim News Agency via AP Photo)

Cole Yeoman steps over a large crack along River Road, Avonside on February 25, 2011 in Christchurch, New Zealand. The death toll has risen to 113 and the hope for finding survivors is fading as rescuers search through debris for over 200 still missing following a 6.3 magnitude earthquake that struck Christchurch on Tuesday. The quake, which was an aftershock of a 7.1 magnitude quake that struck the South Island city on September 4, 2010, has seen damage and fatalities far exceeding those of the original. (Photo by Martin Hunter/Getty Images). CHRISTCHURCH, NEW ZEALAND – FEBRUARY 25

South Korean university students prepare for an establishment ceremony of the Reserve Officer Training Corps (ROTC) for female cadets at Sookmyung Women's University on December 10, 2010 in Seoul, South Korea. The South Korean defense ministry has agreed to admit women into it's college-based Reserve Officers' Training Program for the first time since the program began in 1963. (Photo by Chung Sung-Jun/Getty Images)

A group of children and their dog playing an Easter game in Cardiff. The game involves trying to eat an Easter egg off a piece of string without using their hands. (Photo by Richards/Fox Photos/Getty Images). 26th March 1937

A Chinese girl touches the gun of a relievo featuring Chinese soldiers fighting with Japanese troops during World War II at an exhibition at the Anti-Japan War Museum to mark the 60th Anniversary of the Victory of the Chinese People's War of Resistance Against Japan on August 18, 2005 in Beijing, China. (Photo by Cancan Chu/Getty Images)

The Tribute in Light is seen behind the Empire State Building on September 10, 2011 in New York City. The Tribute in Light is an art installation honoring those who perished in the 9/11 attacks. New York City and the nation are preparing for the tenth anniversary of the terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people at the World Trade Center. (Photo by Mario Tama/Getty Images)