Two boys look out from the Mangueira slum towards the Maracana Stadium that is hosting the Rio's 2016 Summer Olympics opening ceremonies, in Rio de Janeiro, Brazil, Friday, August 5, 2016. (Photo by Leo Correa/AP Photo)

A resident removes mud on a street brought by monsoon rains in San Mateo, Rizal, Philippines, August 14, 2016. (Photo by Erik De Castro/Reuters)

Many of the 12 million people who entered the US through New York’s Ellis Island wore traditional dress from their homelands. Here: A Ruthenian woman circa 1906 from the region historically inhabiting the kingdom of the Rus, incorporating parts of modern-day Slavic speaking countries. Her outfit consists of a shirt and underskirt made from linen embroidered with traditional floral-based patterns. (Photo by Augustus Francis Sherman/New York Public Library/The Guardian)

Activists and supporters of Ukrainian nationalist groups light flares during a rally to mark the third anniversary of the Euromaidan Revolution in downtown Kiev, Ukraine, 21 November 2016. About one thousand activists took park in the rally during which they burned tires on the Independence Square, destroyed the Russian bank Sberbank and broke windows in the office of a Ukrainian politician Viktor Medvedchuk, according to Ukrainian media. (Photo by Roman Pilipey/EPA)

The “Yama” (Pit) memorial is seen in the centre of Minsk May 5, 2015. The memorial is dedicated of the destruction of the Minsk ghetto during World War Two, when several hundred thousands of Jews were slaughtered. Belarus will mark Victory Day on May 9, the 70th anniversary of the Soviet Union's victory over Nazi Germany. (Photo by Vasily Fedosenko/Reuters)

A 20 metre high spiral staircase in a tower used as an emergency exit, is seen inside a Federal Reserve bank (Bundesbank) bunker, prior to the bunker's official opening to the public in Cochem, Germany, March 18, 2016. West Germany's Central Bank (Deutsche Bundesbank) stored some 20 billion German marks of emergency notes in two underground bunkers, one in Frankfurt the other in Cochem, between 1964-1988 during the cold war. (Photo by Kai Pfaffenbach/Reuters)

Justin Nelzen, in red vest, joins others as they work to rescue up to 70 horses along Cypresswood Drive near Humble along Cypress Creek, Monday, April 18, 2016, in Houston. More than a foot of rain fell Monday in parts of Houston, submerging scores of subdivisions and several major interstate highways, forcing the closure of schools and knocking out power to thousands of residents who were urged to shelter in place. (Photo by Mark Mulligan/Houston Chronicle via AP Photo)

The battle by Jose Garcia, US. Category: bird behaviour. A great white heron (Ardea herodias occidentalis) fighting a green snake in the Florida Everglades. The fight lasted for nearly 20 minutes with the heron having to release its prey. (Photo by Jose Garcia/2017 Bird Photographer of the Year Awards)