anchor.diff:  
   import 'package:args/args.dart';
   import 'package:coverage/coverage.dart';
  -import 'package:path/path.dart';
  +import 'package:path/path.dart' as p;
   
   /// [Environment] stores gathered arguments information.
   class Environment {
  
positive.code:   if (args['out'] == 'stdout') {
      env.output = stdout;
    } else {
      var outpath = absolute(normalize(args['out']));
      var outfile = new File(outpath)..createSync(recursive: true);
      env.output = outfile.openWrite();
    }
  
negative.code: 
    env.sdkRoot = args['sdk-root'];
    if (env.sdkRoot != null) {
      env.sdkRoot = p.normalize(p.join(p.absolute(env.sdkRoot), 'lib'));
      if (!FileSystemEntity.isDirectorySync(env.sdkRoot)) {
        fail('Provided SDK root "${args["sdk-root"]}" is not a valid SDK '
            'top-level directory');
  