RMSSE and MASE from fpp3 and fpp2

[newsagent]

I would like to see the source code used for the scaled errors in particular the RMSSE and MASE from fpp3 (https://otexts.com/fpp3/accuracy.html) and MASE from fpp2 (https://otexts.com/fpp2/accuracy.html)

I am interested mainly for fpp2 as a starting point before moving to fpp3
Would it be possible to have the links that lead to these codes so that I can understand better how they are constructed in R?

[robjhyndman]

We use open source software. All the code is available in the relevant packages. The forecast package is at https://github.com/robjhyndman/forecast/, while the fabletools package is at https://github.com/tidyverts/fabletools/ Search for whatever function you want.