Ukrainian President Petro Poroshenko gestures during a news conference in Kiev, Ukraine, June 5, 2015. REUTERS/Mykhailo Markiv/Ukrainian Presidential Press Service/Pool

An armed youth loyal to the Houthi movement takes part in a protest against the Saudi-backed exiled government deciding to cut off the Yemeni central bank from the outside world, in the capital Sanaa, Yemen August 25, 2016. (Photo by Mohamed al-Sayaghi/Reuters)

A general view of Stonehenge during the annual Perseid meteor shower in the night sky in Salisbury Plain, southern England August 13, 2013. The Perseid meteor shower is sparked every August when the Earth passes through a stream of space debris left by comet Swift-Tuttle. Picture taken using a long exposure. (Photo by Kieran Doherty/Reuters)

In this May 17, 2015, photo, two men walk past pagodas at Ngwe Saung beach, Pathein township, about 145 miles from Yangon, Myanmar. (Photo by Khin Maung Win/AP Photo)

A man works on “Long Ma”, a creation by La Machine production company, during a media visit to “A Journey to Nantes” (Le Voyage a Nantes) art festival in Nantes, France, June 30, 2015. The art festival will run from July 3 to August 30. (Photo by Stephane Mahe/Reuters)

The legendary US photographer’s favourite shots of creatures and how they interact with humans feature in “Animals”, his latest book. Here: A boy rests against a cow, Kathmandu, Nepal, 2013. “Cows have been designated the national animal in Nepal. They roam freely, and are considered sacred by the 80% of Nepalis who are Hindu”. (Photo by Steve McCurry/The Guardian)

A clothing shop displays its merchandise in the rebel-controlled city of Idlib, Syria November 7, 2015. (Photo by Ammar Abdullah/Reuters)

A peformance artist attends an election rally for Cameroon presidential candidate for the opposition Univers party, Cabral Libii in Yaounde, Cameroon 06 October 2018. Africa's oldest president Paul Biya who has been in power since 1982 is up against eight candidates when voters go to the polls 07 October 2018. 6.9 million registered voters will head to the polls but marginalised anglophone separatists in the North West and South West of the country threaten to disrupt the elections. (Photo by Nic Bothma/EPA/EFE)