Twelve: Remove unused function

        private val lines = mutableListOf<TempLine>()

        /**

         * Add a new line.

         *

         * @param line The [Line]

         */

        fun addLine(line: Line) = apply {

            lines.add(

                TempLine(

                    text = line.text,

                    startMs = line.durationMs?.first,

                    endMs = line.durationMs?.last,

                )

            )

        }

        /**

         * Add a new line. If necessary, end instant will be calculated from the other lines.

         *