Removed ArgResult in lib/docgen.dart and removed top level variables.

pkg/docgen/bin/docgen.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:logging/logging.dart';
 
 import '../lib/docgen.dart';
 
 /**
  * Analyzes Dart files and generates a representation of included libraries, 
  * classes, and members. 
  */
 void main() {
   logger.onRecord.listen((record) => print(record.message));
-  var results = initArgParser().parse(new Options().arguments);
-  if (results['help']) return;  
-  docgen(results);
+  var results = _initArgParser().parse(new Options().arguments);
+  
+  var outputToYaml = results['yaml'] || results['output-format'] == 'yaml';
+  var outputToJson = results['json'] || results['output-format'] == 'json';
+  if (outputToYaml && outputToJson) {
+    throw new ArgumentError('Cannot have contradictory output flags.');
+  }
+  outputToYaml = outputToYaml || !outputToJson;
+  
+  docgen(results.rest, 
+      packageRoot: results['package-root'], 
+      outputToYaml: outputToYaml,  
+      includePrivate: results['include-private'], 
+      includeSdk: results['parse-sdk'] || results['include-sdk'], 
+      parseSdk: results['parse-sdk']);
 }
 
 /**
  * Creates parser for docgen command line arguments. 
  */
-ArgParser initArgParser() {
+ArgParser _initArgParser() {
   var parser = new ArgParser();
   parser.addFlag('help', abbr: 'h', 
       help: 'Prints help and usage information.', 
       negatable: false, 
       callback: (help) {
         if (help) {
           logger.info(parser.getUsage());
           logger.info(USAGE);
+          exit(0);
         }
       });
   parser.addFlag('verbose', abbr: 'v', 
       help: 'Output more logging information.', negatable: false, 
       callback: (verbose) {
         if (verbose) Logger.root.level = Level.FINEST;
       });
   parser.addOption('output-format', abbr: 'o', 
       help: 'Sets the output format.', 
       allowed: ['yaml', 'json'], 
       allowedHelp: {'yaml' : 'Outputs to YAML. (Default)', 
         'json' : 'Outputs to JSON.'});
   parser.addFlag('yaml', abbr: 'y', 
       help: 'Same as output-format=yaml.', negatable: false);
   parser.addFlag('json', abbr: 'j', 
       help: 'Same as output-format=json.', negatable: false);
   parser.addFlag('include-private', 
       help: 'Flag to include private declarations.', negatable: false);
   parser.addFlag('include-sdk', 
       help: 'Flag to parse SDK Library files.', negatable: false);
   parser.addFlag('parse-sdk', 
       help: 'Parses the SDK libraries only.', 
       defaultsTo: false, negatable: false);
   parser.addOption('package-root', 
       help: "Sets the package root of the library being analyzed.");
   
   return parser;
 }