Two children jumping through a water hydrant's shower on a New York street. They have come from a neighbouring co-educational playgroup organised by the city's Police Department. (Photo by Orlando/Getty Images). 1950

The Pied Piper of Hamelin, actually city tourism employee Michael Boyer, leads local children dressed as rats through a quiet street on November 19, 2012 in Hameln, Germany. The Pied Piper (in German: Der Rattenfaenger), is one of the many stories featured in the collection of fairy tales collected by the Grimm brothers, and the 200th anniversary of the first publication of the stories will take place this coming December 20th. Boyer, a U.S. citizen who has lived in Hameln for 15 years, and city children regularly perform a reenactment of the Pied Piper tale throughout the summer months. The Grimm brothers collected their stories from oral traditions in the region between Frankfurt and Bremen in the early 19th century, and the works include such global classics as Sleeping Beauty, Little Red Riding Hood, Rapunzel, Cinderella and Hansel and Gretel. (Photo by Sean Gallup)

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

From the waters edge a New York policeman urges two young children to put their bathing costumes back on. (Photo by Ed Clarity/Keystone/Getty Images). July 1949

Rohingya refugee children pictured in a camp in Cox's Bazar, Bangladesh, September 19, 2017. With a mass exodus of Rohingya Muslims sparking accusations of ethnic cleansing from the United Nations and others, Myanmar leader Aung San Suu Kyi on Tuesday said her country does not fear international scrutiny and invited diplomats to see some areas for themselves. (Photo by Cathal McNaughton/Reuters)

Children residents take a selfie as they wait for the police to dance, an unconventional approach to connect the police with the community in rough neighbourhoods, as part of the “Tirando Barrio” (Marking territory) programme in Saltillo, Northern Mexico September 9, 2016. T-Shirt reads “Street Dancers”. (Photo by Daniel Becerril/Reuters)

A picture shows the blood stained floor of a kindergarten following reported shelling in the rebel-held area of Harasta, on the northeastern outskirts of the capital Damascus, on November 6, 2016. At least four children were killed and 19 people injured in the government strike in Harasta, according to the Syrian Observatory for Human Rights. (Photo by Sameer Al-Doumy/AFP Photo)

A Sumatran Tiger looks at visiting children from it's enclosure during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. The zoo's annual stocktake requires keepers to check on the numbers of every one of the 800 different animal species, including every invertebrate, bird, fish, mammal, reptile, and amphibian. (Photo by Dan Kitwood/Getty Images)