in lib/printer.dart [88:100]
void mark(mark) {
late final SourceLocation loc;
String? identifier;
if (mark is SourceLocation) {
loc = mark;
} else if (mark is SourceSpan) {
loc = mark.start;
if (mark is SourceMapSpan && mark.isIdentifier) identifier = mark.text;
}
_maps.addLocation(loc,
SourceLocation(_buff.length, line: _line, column: _column), identifier);
_loc = loc;
}