diff --git a/lib/args.dart b/lib/args.dart
index 97b47b5..a49c536 100644
--- a/lib/args.dart
+++ b/lib/args.dart
@@ -2,7 +2,7 @@
 // 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.
 
-export 'src/arg_parser.dart';
-export 'src/arg_parser_exception.dart';
-export 'src/arg_results.dart' hide newArgResults;
-export 'src/option.dart' hide newOption;
+export 'src/arg_parser.dart' show ArgParser;
+export 'src/arg_parser_exception.dart' show ArgParserException;
+export 'src/arg_results.dart' show ArgResults;
+export 'src/option.dart' show Option;
diff --git a/lib/src/arg_results.dart b/lib/src/arg_results.dart
index ca0f493..6345076 100644
--- a/lib/src/arg_results.dart
+++ b/lib/src/arg_results.dart
@@ -32,8 +32,8 @@
   /// The option values that were parsed from arguments.
   final Map<String, dynamic> _parsed;
 
-  /// If these are the results for parsing a command's options, this will be the
-  /// name of the command. For top-level results, this returns `null`.
+  /// The name of the command for which these options are parsed, or `null` if
+  /// these are the top-level results.
   final String name;
 
   /// The command that was selected, or `null` if none was.
@@ -49,16 +49,17 @@
   /// `--` was reached.
   final List<String> rest;
 
-  /// The original list of arguments that were parsed.
+  /// The original arguments that were parsed.
   final List<String> arguments;
 
-  /// Creates a new [ArgResults].
   ArgResults._(this._parser, this._parsed, this.name, this.command,
       List<String> rest, List<String> arguments)
       : rest = UnmodifiableListView(rest),
         arguments = UnmodifiableListView(arguments);
 
-  /// Gets the parsed command-line option named [name].
+  /// Returns the parsed ore default command-line option named [name].
+  ///
+  /// [name] must be a valid option name in the parser.
   dynamic operator [](String name) {
     if (!_parser.options.containsKey(name)) {
       throw ArgumentError('Could not find an option named "$name".');
@@ -67,12 +68,12 @@
     return _parser.options[name].getOrDefault(_parsed[name]);
   }
 
-  /// Get the names of the available options as an [Iterable].
+  /// The names of the available options.
   ///
-  /// This includes the options whose values were parsed or that have defaults.
-  /// Options that weren't present and have no default will be omitted.
+  /// Includes the options whose values were parsed or that have defaults.
+  /// Options that weren't present and have no default are omitted.
   Iterable<String> get options {
-    var result = Set<String>.from(_parsed.keys);
+    var result = _parsed.keys.toSet();
 
     // Include the options that have defaults.
     _parser.options.forEach((name, option) {
@@ -87,9 +88,10 @@
   ///
   /// Returns `false` if it wasn't provided and the default value or no default
   /// value would be used instead.
+  ///
+  /// [name] must be a valid option name in the parser.
   bool wasParsed(String name) {
-    var option = _parser.options[name];
-    if (option == null) {
+    if (!_parser.options.containsKey(name)) {
       throw ArgumentError('Could not find an option named "$name".');
     }
 
diff --git a/lib/src/option.dart b/lib/src/option.dart
index 897f968..7fd9160 100644
--- a/lib/src/option.dart
+++ b/lib/src/option.dart
@@ -52,7 +52,7 @@
   /// A map from values in [allowed] to documentation for those values.
   final Map<String, String> allowedHelp;
 
-  /// The value this option will have if the user doesn't explicitly pass it in
+  /// The value this option will have if the user doesn't explicitly pass it.
   final dynamic defaultsTo;
 
   @Deprecated('Use defaultsTo instead.')