go - Why does append() modify the provided slice? (See example)

Question

You can run the example code on Go Playground.

Here is the code:

package main

import "fmt"

func main() {
    numbers := []int{1, 2, 3, 4, 5}

    fmt.Println(numbers)
    _ = append(numbers[0:1], numbers[2:]...)
    fmt.Println(numbers)
}

Output:

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

Why was the numbers slice modified by append? Is this expected behavior and if yes, could you explain to me why? I thought append doesn't modify its arguments.

Answer 1

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