in lib/src/span.dart [140:153]
String messageMultiple(
String message, String label, Map<SourceSpan, String> secondarySpans,
{bool color = false, String? primaryColor, String? secondaryColor}) {
final buffer = StringBuffer()
..write('line ${start.line + 1}, column ${start.column + 1}');
if (sourceUrl != null) buffer.write(' of ${p.prettyUri(sourceUrl)}');
buffer
..writeln(': $message')
..write(highlightMultiple(label, secondarySpans,
color: color,
primaryColor: primaryColor,
secondaryColor: secondaryColor));
return buffer.toString();
}