I’ve just started learning go. I’m trying to append some strings to ffmpegArgs slice but when I try to append ffmpegArgs[3:]

I’m aware that in go 1.21 I can use the slices.Insert func, but I don’t understand why the append statement throws error.

        ffmpegArgs := []string{
            "-ss",
            inpoint,
            "-i",
            inputPath,
            "-c",
            "copy",
            outputPath,
        }

        if outpoint != "0" {
            // ffmpegArgs = slices.Insert(ffmpegArgs, 2, "-to", outpoint)
            ffmpegArgs = append(ffmpegArgs[:3], "-to", outpoint, ffmpegArgs[3:]...) // this line errors
        }