anchor.diff:          if (constraint == null) {
             constraint = '';
           } else if (constraint is Map) {
  -          constraint = '??complex??';
  +          constraint = constraint.toString();
           }
   
           var dep = new Dependency._(key, constraint, isDev);
  
positive.code:   final bool isDevDependency;
  
    Dependency._(this.name, String versionConstraint, this.isDevDependency)
        : this.versionConstraint = new VersionConstraint.parse(versionConstraint);
  
    static Set<Dependency> getDependencies(Map<String, dynamic> yaml) {
      var deps = new Set<Dependency>();
  
negative.code:     return '$name$devStr $versionConstraint';
    }
  }
  
  VersionConstraint _parseOrNull(String input) {
    try {
      return new VersionConstraint.parse(input);
    } on FormatException catch (e) {
      return VersionConstraint.empty;
    }
  }
  