Migrants with a stick, stones and knife fight with each other after a brawl erupted over a place in an overcrowded train heading to the Serbian border at the train station in Gevgelija, The Former Yugoslav Republic of Macedonia, 14 August 2015. (Photo by Georgi Licovski/EPA/EFE)

Eagle Prime (MK3), a giant robot by MegaBots Inc. which manufactures giant piloted humanoid fighting robots headquartered in Berkeley, California on October 18, 2017. (Photo by Courtesy Michael Mauldin/Reuters/MegaBots Inc)

A cyclist climbs over a tree fallen atop a car after a heavy storm in Amsterdam, the Netherlands, July 25, 2015. One person was killed as the most severe July storm ever recorded in the Netherlands swept across the country on Saturday, delaying flights and disrupting road and rail traffic. Dozens of flights were delayed at Amsterdam's Schiphol Airport and authorities warned travellers not to take to the road as gale-force winds and rain lashed the country, prompting the meteorological service to issue a “Code Red” warning. (Photo by Cris Toala Olivares/Reuters)

A member of the mainly Christian “anti-balaka” (anti-machete) militia trains in the Boeing neighbourhood of Bangui, Central African Republic, on February 24, 2014. (Photo by Fred Dufour/AFP Photo)

A child blowing confetti from her hands during a Carnival parade in Cyprus' coastal city of Limassol, Sunday, March 13, 2016. Limassol's long-established parade is Cyprus' biggest and most famous, drawing revelers from across the east Mediterranean island. This year's parade drew huge crowds as people sought lighthearted reprieve from the bailed-out country's recession. The parade marks the start of the 40-day fasting period of Lent in the run-up to the Orthodox Christian Easter. (Photo by Petros Karadjias/AP Photo)

U.S. President Donald Trump boards Air Force One to depart for Vietnam from Beijing Airport in Beijing, China on November 10, 2017. (Photo by Jonathan Ernst/Reuters)

A woman poses for a photograph in front of a 3D painting at HK 3D Museum in Hong Kong June 26, 2014. (Photo by Tyrone Siu/Reuters)

A young vendor hawks food on a market in Kara in the state of Ogun, on September 23, 2015. Nigeria imposed tight movement restrictions in the restive northeast after Boko Haram bombings that killed more than 100 raised fears of fresh attacks over the Eid al-Adha festival. The military said the use of all vehicles would be banned throughout Borno state during the Muslim festival, which is known as Sallah in Nigeria and marked with two days' public holiday from Thursday. (Photo by Pius Utomi Ekpei/AFP Photo)