anchor.diff:  
     openIssues.forEach((issue) {
       if (issue.state == "OPEN") open.add(issue);
  -    if (issue.createdAt.compareTo(opts.from) >= 0 && issue.createdAt.compareTo(opts.to) <= 0) openedThisPeriod.add(issue);
  -  });
  -  
  -  closedIssues.forEach((issue) {
  -    if (issue.state == "CLOSED" && issue.closedAt.compareTo(opts.from) >= 0 && issue.closedAt.compareTo(opts.to) <= 0) closedThisPeriod.add(issue);
  -    if (issue.createdAt.compareTo(opts.from) >= 0 && issue.createdAt.compareTo(opts.to) <= 0) openedThisPeriod.add(issue);
  +    if (issue.createdAt.compareTo(opts.from) >= 0 &&
  +        issue.createdAt.compareTo(opts.to) <= 0) openedThisPeriod.add(issue);
     });
   
  -  var fromStamp = opts.from.toIso8601String().substring(0,10);
  -  var toStamp = opts.to.toIso8601String().substring(0,10);
  +  closedIssues.forEach((issue) {
  +    if (issue.state == "CLOSED" &&
  +        issue.closedAt.compareTo(opts.from) >= 0 &&
  +        issue.closedAt.compareTo(opts.to) <= 0) closedThisPeriod.add(issue);
  +    if (issue.createdAt.compareTo(opts.from) >= 0 &&
  +        issue.createdAt.compareTo(opts.to) <= 0) openedThisPeriod.add(issue);
  +  });
   
  -  printHeader(opts);
  +  var fromStamp = opts.from.toIso8601String().substring(0, 10);
  +  var toStamp = opts.to.toIso8601String().substring(0, 10);
   
  -  print('This shows the number of new, open, and closed `P0` issues over the period from');
  +  printHeader(opts, 'TODAUY');
  +
  +  print(
  +      'This shows the number of new, open, and closed `P0` issues over the period from');
     print('${fromStamp} to ${toStamp}.\n\n');
   
     print('### ${open.length} open `P0` issue(s)');
  -  open.forEach((issue) => print(issue.summary(boldInteresting: false, linebreakAfter: true)));
  +  open.forEach((issue) =>
  +      print(issue.summary(boldInteresting: false, linebreakAfter: true)));
   
  -  print('### ${openedThisPeriod.length} `P0` issue(s) opened between ${fromStamp} and ${toStamp}');
  -  openedThisPeriod.forEach((issue) => print(issue.summary(boldInteresting: false, linebreakAfter: true)));
  +  print(
  +      '### ${openedThisPeriod.length} `P0` issue(s) opened between ${fromStamp} and ${toStamp}');
  +  openedThisPeriod.forEach((issue) =>
  +      print(issue.summary(boldInteresting: false, linebreakAfter: true)));
   
  -  print('### ${closedThisPeriod.length} `P0` issue(s) closed between ${fromStamp} and ${toStamp}');
  -  closedThisPeriod.forEach((issue) => print(issue.summary(boldInteresting: false, linebreakAfter: true)));
  +  print(
  +      '### ${closedThisPeriod.length} `P0` issue(s) closed between ${fromStamp} and ${toStamp}');
  +  closedThisPeriod.forEach((issue) =>
  +      print(issue.summary(boldInteresting: false, linebreakAfter: true)));
   
  +  // Bail if we don't care about performance issues.
  +  if (opts.excludePerformance) return;
  +
  +  // Now do the same for performance issues.
  +  var openPerfIssues = await github.search(
  +    owner: 'flutter',
  +    name: 'flutter',
  +    type: GitHubIssueType.issue,
  +    state: GitHubIssueState.open,
  +    labels: ['severe: performance'],
  +  );
  +
  +  var closedPerfIssues = await github.search(
  +    owner: 'flutter',
  +    name: 'flutter',
  +    type: GitHubIssueType.issue,
  +    state: GitHubIssueState.closed,
  +    labels: ['severe: performance'],
  +  );
  +
  +  open = List<Issue>();
  +  openedThisPeriod = List<Issue>();
  +  closedThisPeriod = List<Issue>();
  +
  +  openPerfIssues.forEach((issue) {
  +    if (issue.state == "OPEN") open.add(issue);
  +    if (issue.createdAt.compareTo(opts.from) >= 0 &&
  +        issue.createdAt.compareTo(opts.to) <= 0) openedThisPeriod.add(issue);
  +  });
  +
  +  closedPerfIssues.forEach((issue) {
  +    if (issue.state == "CLOSED" &&
  +        issue.closedAt.compareTo(opts.from) >= 0 &&
  +        issue.closedAt.compareTo(opts.to) <= 0) closedThisPeriod.add(issue);
  +    if (issue.createdAt.compareTo(opts.from) >= 0 &&
  +        issue.createdAt.compareTo(opts.to) <= 0) openedThisPeriod.add(issue);
  +  });
  +
  +  printHeader(opts, 'performance');
  +
  +  print(
  +      'This shows the number of new, open, and closed `severe: performance` issues over the period from');
  +  print('${fromStamp} to ${toStamp}.\n\n');
  +
  +  print('### ${open.length} open `severe: performance` issue(s)\n');
  +
  +  print(
  +      '### ${openedThisPeriod.length} `severe: performance` issue(s) opened between ${fromStamp} and ${toStamp}');
  +  openedThisPeriod.forEach((issue) =>
  +      print(issue.summary(boldInteresting: false, linebreakAfter: true)));
  +
  +  print(
  +      '### ${closedThisPeriod.length} `severe: performance` issue(s) closed between ${fromStamp} and ${toStamp}');
  +  closedThisPeriod.forEach((issue) =>
  +      print(issue.summary(boldInteresting: false, linebreakAfter: true)));
   }
  
positive.code: import 'package:args/args.dart';
  import 'dart:io';
  
  
  
  class Options  {
    final _parser = ArgParser(allowTrailingOptions: false);
    ArgResults _results;
    DateTime get from => DateTime.parse(_results['from']);
    DateTime get to => DateTime.parse(_results['to']);
    int get exitCode => _results == null ? -1 : _results['help'] ? 0 : null;
  
    Options(List<String> args) {
      _parser
        ..addFlag('help', defaultsTo: false, abbr: 'h', negatable: false, help: 'get usage')
        ..addOption('from', defaultsTo: DateTime.now().subtract(Duration(hours: 24 * 7)).toString(), abbr: 'f', help: 'from date, ISO format yyyy-mm-dd')
        ..addOption('to', defaultsTo: DateTime.now().toIso8601String(), abbr: 't', help: 'to date, ISO format yyyy-mm-dd');
      try {
        _results = _parser.parse(args);
        if (_results['help'])  _printUsage();
      } on ArgParserException catch (e) {
        print(e.message);
        _printUsage();
  
negative.code:   if (opts.exitCode != null) exit(opts.exitCode);
    final token = Platform.environment['GITHUB_TOKEN'];
    final github = GitHub(token);
    final closedRange =
        DateRange(DateRangeType.range, start: opts.from, end: opts.to);
    final openedRange = DateRange(DateRangeType.range,
        start: opts.to.subtract(Duration(hours: 24 * 7)), end: opts.to);
  
    var openIssues = await github.search(
      owner: 'flutter',
      name: 'flutter',
      type: GitHubIssueType.issue,
      state: GitHubIssueState.open,
      labels: ['P0'],
    );
  
    var closedIssues = await github.search(
      owner: 'flutter',
      name: 'flutter',
      type: GitHubIssueType.issue,
      state: GitHubIssueState.closed,
      labels: ['P0'],
  