in src/content/line.rs [246:262]
fn test_pad_line_left() -> anyhow::Result<()> {
let mut test: Line = Line(vec!["test".try_into()?, "ok".try_into()?]);
let mut new_test: Line = test.clone();
test.0.insert(0, " ".repeat(4).try_into()?);
new_test.pad_left(4);
assert_eq!(test, new_test);
new_test.pad_left(6);
test.0.insert(0, " ".repeat(6).try_into()?);
assert_eq!(test, new_test);
new_test.pad_left(10);
test.0.insert(0, " ".repeat(10).try_into()?);
assert_eq!(test, new_test);
Ok(())
}