Function render_text 

pub fn render_text(report: &DiffReport) -> String

Renders a report as a human-readable summary: the report verdict on the first line, then one indented line per change. A change whose category has no heading is listed first, in report order; then each heading is printed once, as its own line ending in a colon, followed by the changes under it, in report order. Headings come in CATEGORIES order.

After the contract changes come the system headings (rsdl reference §14): each heading that has a change on its own line, then one indented line per change under it, in the path: before -> after form and with no verdict.