这段代码在builti.go：

// The append built-in function appends elements to the end of a slice. If
// it has sufficient capacity, the destination is resliced to accommodate the
// new elements. If it does not, a new underlying array will be allocated.
// Append returns the updated slice. It is therefore necessary to store the
// result of append, often in the variable holding the slice itself:
//  slice = append(slice, elem1, elem2)
//  slice = append(slice, anotherSlice...)
// As a special case, it is legal to append a string to a byte slice, like this:
//  slice = append([]byte("hello "), "world"...)
func append(slice []Type, elems ...Type) []Type

最后一行使我感到非常困惑。我不知道的意思...Type。

这些是其他代码：

package main

import "fmt"

func main() {
   s := []int{1,2,3,4,5}
   s1 := s[:2]
   s2 := s[2:]
   s3 := append(s1, s2...)
   fmt.Println(s1, s2, s3)
}

结果是

[1 2] [3 4 5] [1 2 3 4 5]

我猜想的功能...是从中选择所有元素elems，但是我还没有找到正式的解释。它是什么？