don't leave with the idea that you should always have a begin method in C++,
Whilst this is true it does no harm and also helps to make the code self documenting when the begin() method is called from setup() This is similar to the fact that because pins default to being inputs then if that is what is required there is never any need to do pinMode(buttonPin, INPUT) but doing so clarifies the use of the pin, as should the name given it