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Faced with the greatest migration of people in Europe since World War Two, some European governments have built fences to stop refugees from crossing their borders. In the US too, presidential hopeful Donald Trump wants to build a wall to keep out Mexican migrants. We hear what Fernando Gonzalez, chief executive officer of Mexico's Cemex, one of the world's largest construction companies, makes of that. Also, we speak to John Edge, founder of ID2020 which aims to give every child born after 2020 a self-sovereign digital identity. It's a project built on blockchain technology - the system that supports the virtual currency bitcoin - and the hope is it could help solve problems migrants and refugees face in proving who they are. Plus our regular contributor James Srodes reflects on why populations are always so averse to change, especially that brought about by an influx of foreign people.

(Photo by Jeff J Mitchell/Getty Images)