Get rid of all the library tags.

lib/src/yaml_node.dart

 // Copyright (c) 2012, 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.
 
-library yaml.yaml_node;
-
 import 'dart:collection' as collection;
 
 import 'package:collection/collection.dart';
 import 'package:source_span/source_span.dart';
 
 import 'event.dart';
 import 'null_span.dart';
 import 'style.dart';
 import 'yaml_node_wrapper.dart';
 
@@ skipping 160 matching lines @@
 
   String toString() => value.toString();
 }
 
 /// Sets the source span of a [YamlNode].
 ///
 /// This method is not exposed publicly.
 void setSpan(YamlNode node, SourceSpan span) {
   node._span = span;
 }