Functions

To return multiple values from a function

// Returns two decks

func deal(cards deck, handSize int) (deck, deck) {
  return d[:handSize], d[handSize:]
}

To capture both function outputs:

deck1, deck2 := deal(cards, 5)

A lot of functions return an error type:

byteslice, err := ioutil.ReadFile(filename)
if err != nil

Function Literal (unnamed, anonymous, lambda)

func() {
  // some code...
}()