These two young siblings appear to cling on to a tree for dear life and even hold hands as they learn the ropes of climbing, on June 25, 2013. (Photo by Tim Fitzharris/Minden/Solent)

A groom leads his horse in the equine pool after working out on the track, during early morning workouts for the upcoming Derby race in Mumbai January 29, 2015. (Photo by Danish Siddiqui/Reuters)

An election poster calling for the legalisation of marijuana and featuring internet meme “Grumpy Cat” hangs outside the Pirate Party's campaign headquarters in Berlin on August 16, 2013. The Pirates, who to everyone's surprise were elected into Berlin's regional parliament in September 2011, are trying to capitalise on their recent electoral gains in upcoming parliamentary elections, running on a platform of transparency in government. Germany goes to the polls on September 22, 2013. Placard reads: “Hurry up, my dope is everything”. (Photo by John Macdougall/AFP Photo)

Men dressed as soldiers pose with models before the opening of the Gamescom 2013 fair in Cologne,Germany, on August 23, 2013. The Gamescom convention is Europe's largest video games trade fair. (Photo by Ina Fassbender/Reuters)

A mouse rides on the back of a frog in floodwaters in the northern Indian city Lucknow June 30, 2006. (Photo by Pawan Kumar/Reuters)

A masked reveller poses in San Marco Piazza during the Venice Carnival, January 30, 2016. (Photo by Alessandro Bianchi/Reuters)

A Palestinian woman is assisted at the site of an Israeli strike on a house in Rafah in the southern Gaza Strip on October 30, 2023. (Photo by Reuters/Stringer)

Dogs perform during “Stars and starlets”, a new programme, at the National Circus in the Ukrainian capital of Kiev April 30, 2015. (Photo by Gleb Garanich/Reuters)