it's not outdated, and it's a fine example - reading the go stdlib is the best way to learn the language well, honestly. The missing return values on 64 and 69

it's not outdated, and it's a fine example - reading the go stdlib is the best way to learn the language well, honestly. The missing return values on 64 and 69 are the "Named Return Values" thing that OP mentions - the returns are the variables named in the function declaration.