Inside a function, the := short assignment statement can be used in place of a var declaration with implicit type.

Outside a function, every construct begins with a keyword (var, func, and so on) and the := construct is not available.

package main import "fmt"var k int = 3var k2 = 3//k3 := 4 //non-declaration statement outside function bodyfunc main() {    var i, j int = 1, 2     k := 3    c, python, java := true, false, "no!"    fmt.Println(i, j, k, c, python, java)}

A Tour of Go Short variable declarations