A woman waits at a polio immunisation health centre, in Maiduguri, Borno State, Nigeria, August 29, 2016. Nigeria's military has liberated large swathes of land from Boko Haram but a ride with an army convoy, all guns firing for fear of ambush, shows how far the northeast is from normality after a brutal Islamist insurgency that has displaced millions. (Photo by Afolabi Sotunde/Reuters)

Colombian police help carry people's household belongings across the Tachira River from Venezuela, top, to Colombia, on the border that separates San Antonio del Tachira, Venezuela from Villa del Rosario, Colombia, Tuesday, August 25, 2015, during a mass exodus of Colombians. Venezuelan President Nicolas Maduro vowed to extend a crackdown on illegal migrants from neighboring Colombia he blames for rampant crime and widespread shortages, while authorities across the border struggled to attend to droves of returning deportees. (Photo by Eliecer Mantilla/AP Photo)

A female soldier from the honour guards prepares for a welcoming ceremony for Uruguay's President Tabare Vazquez at the Great Hall of the People in Beijing, China, October 18, 2016. (Photo by Jason Lee/Reuters)

Labourers unload gravel from a boat docked in Dala township, opposite Yangon city, Myanmar, November 12, 2015. (Photo by Olivia Harris/Reuters)

A picturesque supercell formation in the northwest of Booker, Texas from June 2013. (Photo by Mike Olbinski/Barcroft Media)

#Petheadz – is an Instagram series by Zach Rose, a 23 year old photographer/filmmaker from Toronto. (Photo by Zach Rose)

A volunteer approaches a male toad to pick him up from a road near Berlin on March 18, 2012 in Gueterfelde, Germany. (Photo by Sean Gallup/Getty Images)

A man crosses Canal Street in the wind and rain from Hurricane Isaac August 29, 2012. (Photo by David J. Phillip/Associated Press)