Why doesn't copy() copy a slice in Go? Or am I doing something wrong?

Hello everyone! I recently started learning Go and encountered an unclear problem when working with slices. I needed to duplicate one slice into another so that I could later modify the copy independently of the original. I read that there is a built-in `copy()` function for this. I wrote this code: ```go package main import "fmt" func main() { original := []int{1, 2, 3, 4, 5} var copySlice []int copy(copySlice, original) fmt.Println("original:", original) fmt.Println("copy:", copySlice) } ``` But the output gave me an empty slice! `copySlice` remained `[]`. I expected that after `copy()`, `copySlice` would have the same elements as `original`. Then I tried another approach — first declared a slice with length but without values: ```go copySlice2 := make([]int,