Function redraw_frame 

pub fn redraw_frame(
    out: &mut impl Write,
    frame: &str,
    prev_lines: usize,
    cols: Option<usize>,
) -> usize

In-place terminal redraw of one frame. Assumes the cursor parks on the previous frame’s last line (no trailing newline). Returns the new frame’s line count so the caller can pass it back as prev_lines.