en PBN version: https://planb.network/sw/courses/dev103-bbf08a64-84ca-11f0-9d7a-c3c481a45799
en github version: https://github.com/PlanB-Network/bitcoin-educational-content/blob/dev/courses/dev103/en.md
sw github version: https://github.com/PlanB-Network/bitcoin-educational-content/blob/dev/courses/dev103/sw.md