Hello, welcome to the Ruby Advent Calendar 2017. The idea is: 25 Days of Ruby Gems / Libraries from December 1 to December 25. Let’s kick off the series on Day 1 with blockchain-lite - Build your own blockchains with crypto hashes; revolutionize the world with blockchains, blockchains, blockchains one block at a time! Cheers. PS: You’re welcome to send in your articles (about your library / gem of choice) too!