anchor.diff:    /// excluding any listen in `seen`.
     Iterable<String> getTransitiveDependenciesFor(String package, { Set<String> seen }) sync* {
       seen ??= new Set<String>();
  +    if (!_dependencyTree.containsKey(package)) {
  +      // We have no transitive dependencies extracted for flutter_sdk packages
  +      // because they were omitted from pubspec.yaml used for 'pub upgrade' run.
  +      return;
  +    }
       for (String dependency in _dependencyTree[package]) {
         if (!seen.contains(dependency)) {
           yield dependency;
  
positive.code:   result.writeln('dependencies:');
    overrides.writeln('dependency_overrides:');
    for (PubspecDependency dependency in dependencies)
      dependency.describeForFakePubspec(result, overrides);
    result.write(overrides.toString());
    return result.toString();
  }
  
negative.code:             // dependency lines.
              if (!data.isTransitive) {
                assert(!done.contains(data.name));
                if (data.kind == DependencyKind.normal) {
                  // This is a regular dependency, so we need to update the
                  // version number.
  