Function wrap_unit 

pub fn wrap_unit(
    text: &str,
    start: usize,
    end: usize,
    form: TextForm,
    wrap: Wrap,
    width: usize,
) -> Vec<Row>

Wrap bytes start..end of text to rows of at most width cells. Raw text spaces its tabs to stops of four and marks controls; escaped text is the literal, quoted at the value’s two ends.