... in Golang

func append(slice []T, elements ...T) []T

x := []int{1,2,3}
x = append(x, 4, 5, 6)
fmt.Println(x) // [1 2 3 4 5 6]

// append slice to slice, use ...
x := []int{1,2,3}
y := []int{4,5,6}
x = append(x, y...)
fmt.Println(x)