All our code will be hosted in a single Solidity file, so first create an empty file called tontine.sol in Truffle’s contracts/ folder using touch contracts/tontine.sol.
If you don’t like to copy the code from books, no worries, you can grab the code from this GitHub repository: https://github.com/bellaj/TontineGame/blob/master/tontine/contracts/tontine.sol.