Go 1.13 Release Notes(golang.org)

    var a, b = f()
    var a, b = f() // NO

    var a, b = f()
    a, b := f() // NO

    
    // note that the second declaration only partially overlaps with the first
    var a, b = f()
    var a, c = f() // NO

    var a, b = f()
    a, c := f() // yes

    if err := fn(); err != nil {
    }
    // the result of fn does not affect the identifier err
    // in the enclosing scope

    var err error
    if err = fn(); err != nil {
    }
    // err has the result of fn here

    package main
    import "fmt"
    
    func main() {
        var m = map[interface{}]int {
            [2]int{1, 2}: 12,
            [3]int{1, 2, 4}: 123,
            [4]int{1, 2, 3, 4}: 1234,
        }
        fmt.Println(m)
    }