Function report 

pub fn report(name: &str, text: &str, span: Span, message: &str) -> String

Reports message at span of the document name, whose text is text: a name:line:column: message line, then the span’s first line with the span underlined to that line’s end. Columns count code points, a tab as one, as Location::column does. A span past the text’s end is put at its end.