diff --git a/lib/parser.dart b/lib/parser.dart
index 95aaa9a..0e89e66 100644
--- a/lib/parser.dart
+++ b/lib/parser.dart
@@ -248,13 +248,13 @@ class HtmlParser {
       return enc == 'text/html' || enc == 'application/xhtml+xml';
     } else {
       return htmlIntegrationPointElements
-          .contains(Pair(element.namespaceUri, element.localName));
+          .contains((element.namespaceUri, element.localName));
     }
   }
 
   bool isMathMLTextIntegrationPoint(Element element) {
     return mathmlTextIntegrationPointElements
-        .contains(Pair(element.namespaceUri, element.localName));
+        .contains((element.namespaceUri, element.localName));
   }
 
   bool inForeignContent(Token token, int type) {
@@ -3978,7 +3978,7 @@ class ParseError implements SourceSpanException {
 }
 
 /// Convenience function to get the pair of namespace and localName.
-Pair<String, String?> getElementNameTuple(Element e) {
+(String, String?) getElementNameTuple(Element e) {
   final ns = e.namespaceUri ?? Namespaces.html;
-  return Pair(ns, e.localName);
+  return (ns, e.localName);
 }
diff --git a/lib/src/constants.dart b/lib/src/constants.dart
index abd483b..e70b1e2 100644
--- a/lib/src/constants.dart
+++ b/lib/src/constants.dart
@@ -258,139 +258,139 @@ class Namespaces {
   }
 }
 
-const List<Pair<String, String>> scopingElements = [
-  Pair(Namespaces.html, 'applet'),
-  Pair(Namespaces.html, 'caption'),
-  Pair(Namespaces.html, 'html'),
-  Pair(Namespaces.html, 'marquee'),
-  Pair(Namespaces.html, 'object'),
-  Pair(Namespaces.html, 'table'),
-  Pair(Namespaces.html, 'td'),
-  Pair(Namespaces.html, 'th'),
-  Pair(Namespaces.mathml, 'mi'),
-  Pair(Namespaces.mathml, 'mo'),
-  Pair(Namespaces.mathml, 'mn'),
-  Pair(Namespaces.mathml, 'ms'),
-  Pair(Namespaces.mathml, 'mtext'),
-  Pair(Namespaces.mathml, 'annotation-xml'),
-  Pair(Namespaces.svg, 'foreignObject'),
-  Pair(Namespaces.svg, 'desc'),
-  Pair(Namespaces.svg, 'title')
+const List<(String, String)> scopingElements = [
+  (Namespaces.html, 'applet'),
+  (Namespaces.html, 'caption'),
+  (Namespaces.html, 'html'),
+  (Namespaces.html, 'marquee'),
+  (Namespaces.html, 'object'),
+  (Namespaces.html, 'table'),
+  (Namespaces.html, 'td'),
+  (Namespaces.html, 'th'),
+  (Namespaces.mathml, 'mi'),
+  (Namespaces.mathml, 'mo'),
+  (Namespaces.mathml, 'mn'),
+  (Namespaces.mathml, 'ms'),
+  (Namespaces.mathml, 'mtext'),
+  (Namespaces.mathml, 'annotation-xml'),
+  (Namespaces.svg, 'foreignObject'),
+  (Namespaces.svg, 'desc'),
+  (Namespaces.svg, 'title')
 ];
 
 const formattingElements = [
-  Pair(Namespaces.html, 'a'),
-  Pair(Namespaces.html, 'b'),
-  Pair(Namespaces.html, 'big'),
-  Pair(Namespaces.html, 'code'),
-  Pair(Namespaces.html, 'em'),
-  Pair(Namespaces.html, 'font'),
-  Pair(Namespaces.html, 'i'),
-  Pair(Namespaces.html, 'nobr'),
-  Pair(Namespaces.html, 's'),
-  Pair(Namespaces.html, 'small'),
-  Pair(Namespaces.html, 'strike'),
-  Pair(Namespaces.html, 'strong'),
-  Pair(Namespaces.html, 'tt'),
-  Pair(Namespaces.html, '')
+  (Namespaces.html, 'a'),
+  (Namespaces.html, 'b'),
+  (Namespaces.html, 'big'),
+  (Namespaces.html, 'code'),
+  (Namespaces.html, 'em'),
+  (Namespaces.html, 'font'),
+  (Namespaces.html, 'i'),
+  (Namespaces.html, 'nobr'),
+  (Namespaces.html, 's'),
+  (Namespaces.html, 'small'),
+  (Namespaces.html, 'strike'),
+  (Namespaces.html, 'strong'),
+  (Namespaces.html, 'tt'),
+  (Namespaces.html, '')
 ];
 
 const specialElements = [
-  Pair(Namespaces.html, 'address'),
-  Pair(Namespaces.html, 'applet'),
-  Pair(Namespaces.html, 'area'),
-  Pair(Namespaces.html, 'article'),
-  Pair(Namespaces.html, 'aside'),
-  Pair(Namespaces.html, 'base'),
-  Pair(Namespaces.html, 'basefont'),
-  Pair(Namespaces.html, 'bgsound'),
-  Pair(Namespaces.html, 'blockquote'),
-  Pair(Namespaces.html, 'body'),
-  Pair(Namespaces.html, 'br'),
-  Pair(Namespaces.html, 'button'),
-  Pair(Namespaces.html, 'caption'),
-  Pair(Namespaces.html, 'center'),
-  Pair(Namespaces.html, 'col'),
-  Pair(Namespaces.html, 'colgroup'),
-  Pair(Namespaces.html, 'command'),
-  Pair(Namespaces.html, 'dd'),
-  Pair(Namespaces.html, 'details'),
-  Pair(Namespaces.html, 'dir'),
-  Pair(Namespaces.html, 'div'),
-  Pair(Namespaces.html, 'dl'),
-  Pair(Namespaces.html, 'dt'),
-  Pair(Namespaces.html, 'embed'),
-  Pair(Namespaces.html, 'fieldset'),
-  Pair(Namespaces.html, 'figure'),
-  Pair(Namespaces.html, 'footer'),
-  Pair(Namespaces.html, 'form'),
-  Pair(Namespaces.html, 'frame'),
-  Pair(Namespaces.html, 'frameset'),
-  Pair(Namespaces.html, 'h1'),
-  Pair(Namespaces.html, 'h2'),
-  Pair(Namespaces.html, 'h3'),
-  Pair(Namespaces.html, 'h4'),
-  Pair(Namespaces.html, 'h5'),
-  Pair(Namespaces.html, 'h6'),
-  Pair(Namespaces.html, 'head'),
-  Pair(Namespaces.html, 'header'),
-  Pair(Namespaces.html, 'hr'),
-  Pair(Namespaces.html, 'html'),
-  Pair(Namespaces.html, 'iframe'),
+  (Namespaces.html, 'address'),
+  (Namespaces.html, 'applet'),
+  (Namespaces.html, 'area'),
+  (Namespaces.html, 'article'),
+  (Namespaces.html, 'aside'),
+  (Namespaces.html, 'base'),
+  (Namespaces.html, 'basefont'),
+  (Namespaces.html, 'bgsound'),
+  (Namespaces.html, 'blockquote'),
+  (Namespaces.html, 'body'),
+  (Namespaces.html, 'br'),
+  (Namespaces.html, 'button'),
+  (Namespaces.html, 'caption'),
+  (Namespaces.html, 'center'),
+  (Namespaces.html, 'col'),
+  (Namespaces.html, 'colgroup'),
+  (Namespaces.html, 'command'),
+  (Namespaces.html, 'dd'),
+  (Namespaces.html, 'details'),
+  (Namespaces.html, 'dir'),
+  (Namespaces.html, 'div'),
+  (Namespaces.html, 'dl'),
+  (Namespaces.html, 'dt'),
+  (Namespaces.html, 'embed'),
+  (Namespaces.html, 'fieldset'),
+  (Namespaces.html, 'figure'),
+  (Namespaces.html, 'footer'),
+  (Namespaces.html, 'form'),
+  (Namespaces.html, 'frame'),
+  (Namespaces.html, 'frameset'),
+  (Namespaces.html, 'h1'),
+  (Namespaces.html, 'h2'),
+  (Namespaces.html, 'h3'),
+  (Namespaces.html, 'h4'),
+  (Namespaces.html, 'h5'),
+  (Namespaces.html, 'h6'),
+  (Namespaces.html, 'head'),
+  (Namespaces.html, 'header'),
+  (Namespaces.html, 'hr'),
+  (Namespaces.html, 'html'),
+  (Namespaces.html, 'iframe'),
   // Note that image is commented out in the spec as "this isn't an
   // element that can end up on the stack, so it doesn't matter,"
-  Pair(Namespaces.html, 'image'),
-  Pair(Namespaces.html, 'img'),
-  Pair(Namespaces.html, 'input'),
-  Pair(Namespaces.html, 'isindex'),
-  Pair(Namespaces.html, 'li'),
-  Pair(Namespaces.html, 'link'),
-  Pair(Namespaces.html, 'listing'),
-  Pair(Namespaces.html, 'marquee'),
-  Pair(Namespaces.html, 'men'),
-  Pair(Namespaces.html, 'meta'),
-  Pair(Namespaces.html, 'nav'),
-  Pair(Namespaces.html, 'noembed'),
-  Pair(Namespaces.html, 'noframes'),
-  Pair(Namespaces.html, 'noscript'),
-  Pair(Namespaces.html, 'object'),
-  Pair(Namespaces.html, 'ol'),
-  Pair(Namespaces.html, 'p'),
-  Pair(Namespaces.html, 'param'),
-  Pair(Namespaces.html, 'plaintext'),
-  Pair(Namespaces.html, 'pre'),
-  Pair(Namespaces.html, 'script'),
-  Pair(Namespaces.html, 'section'),
-  Pair(Namespaces.html, 'select'),
-  Pair(Namespaces.html, 'style'),
-  Pair(Namespaces.html, 'table'),
-  Pair(Namespaces.html, 'tbody'),
-  Pair(Namespaces.html, 'td'),
-  Pair(Namespaces.html, 'textarea'),
-  Pair(Namespaces.html, 'tfoot'),
-  Pair(Namespaces.html, 'th'),
-  Pair(Namespaces.html, 'thead'),
-  Pair(Namespaces.html, 'title'),
-  Pair(Namespaces.html, 'tr'),
-  Pair(Namespaces.html, 'ul'),
-  Pair(Namespaces.html, 'wbr'),
-  Pair(Namespaces.html, 'xmp'),
-  Pair(Namespaces.svg, 'foreignObject')
+  (Namespaces.html, 'image'),
+  (Namespaces.html, 'img'),
+  (Namespaces.html, 'input'),
+  (Namespaces.html, 'isindex'),
+  (Namespaces.html, 'li'),
+  (Namespaces.html, 'link'),
+  (Namespaces.html, 'listing'),
+  (Namespaces.html, 'marquee'),
+  (Namespaces.html, 'men'),
+  (Namespaces.html, 'meta'),
+  (Namespaces.html, 'nav'),
+  (Namespaces.html, 'noembed'),
+  (Namespaces.html, 'noframes'),
+  (Namespaces.html, 'noscript'),
+  (Namespaces.html, 'object'),
+  (Namespaces.html, 'ol'),
+  (Namespaces.html, 'p'),
+  (Namespaces.html, 'param'),
+  (Namespaces.html, 'plaintext'),
+  (Namespaces.html, 'pre'),
+  (Namespaces.html, 'script'),
+  (Namespaces.html, 'section'),
+  (Namespaces.html, 'select'),
+  (Namespaces.html, 'style'),
+  (Namespaces.html, 'table'),
+  (Namespaces.html, 'tbody'),
+  (Namespaces.html, 'td'),
+  (Namespaces.html, 'textarea'),
+  (Namespaces.html, 'tfoot'),
+  (Namespaces.html, 'th'),
+  (Namespaces.html, 'thead'),
+  (Namespaces.html, 'title'),
+  (Namespaces.html, 'tr'),
+  (Namespaces.html, 'ul'),
+  (Namespaces.html, 'wbr'),
+  (Namespaces.html, 'xmp'),
+  (Namespaces.svg, 'foreignObject')
 ];
 
 const htmlIntegrationPointElements = [
-  Pair(Namespaces.mathml, 'annotaion-xml'),
-  Pair(Namespaces.svg, 'foreignObject'),
-  Pair(Namespaces.svg, 'desc'),
-  Pair(Namespaces.svg, 'title')
+  (Namespaces.mathml, 'annotaion-xml'),
+  (Namespaces.svg, 'foreignObject'),
+  (Namespaces.svg, 'desc'),
+  (Namespaces.svg, 'title')
 ];
 
 const mathmlTextIntegrationPointElements = [
-  Pair(Namespaces.mathml, 'mi'),
-  Pair(Namespaces.mathml, 'mo'),
-  Pair(Namespaces.mathml, 'mn'),
-  Pair(Namespaces.mathml, 'ms'),
-  Pair(Namespaces.mathml, 'mtext')
+  (Namespaces.mathml, 'mi'),
+  (Namespaces.mathml, 'mo'),
+  (Namespaces.mathml, 'mn'),
+  (Namespaces.mathml, 'ms'),
+  (Namespaces.mathml, 'mtext')
 ];
 
 const spaceCharacters = ' \n\r\t\u000C';
diff --git a/lib/src/treebuilder.dart b/lib/src/treebuilder.dart
index b63395c..781f3f6 100644
--- a/lib/src/treebuilder.dart
+++ b/lib/src/treebuilder.dart
@@ -10,7 +10,6 @@ import '../parser.dart' show getElementNameTuple;
 import 'constants.dart';
 import 'list_proxy.dart';
 import 'token.dart';
-import 'utils.dart';
 
 /// Open elements in the formatting category, most recent element last.
 ///
@@ -113,29 +112,29 @@ class TreeBuilder {
     final exactNode = target is Node;
 
     var listElements1 = scopingElements;
-    var listElements2 = const <Pair<String, String>>[];
+    var listElements2 = const <(String, String)>[];
     var invert = false;
     if (variant != null) {
       switch (variant) {
         case 'button':
-          listElements2 = const [Pair(Namespaces.html, 'button')];
+          listElements2 = const [(Namespaces.html, 'button')];
           break;
         case 'list':
           listElements2 = const [
-            Pair(Namespaces.html, 'ol'),
-            Pair(Namespaces.html, 'ul')
+            (Namespaces.html, 'ol'),
+            (Namespaces.html, 'ul')
           ];
           break;
         case 'table':
           listElements1 = const [
-            Pair(Namespaces.html, 'html'),
-            Pair(Namespaces.html, 'table')
+            (Namespaces.html, 'html'),
+            (Namespaces.html, 'table')
           ];
           break;
         case 'select':
           listElements1 = const [
-            Pair(Namespaces.html, 'optgroup'),
-            Pair(Namespaces.html, 'option')
+            (Namespaces.html, 'optgroup'),
+            (Namespaces.html, 'option')
           ];
           invert = true;
           break;
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index 5c4e359..4f4bd1a 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -1,19 +1,5 @@
 import 'constants.dart';
 
-class Pair<F, S> {
-  final F first;
-  final S second;
-
-  const Pair(this.first, this.second);
-
-  @override
-  int get hashCode => 37 * first.hashCode + second.hashCode;
-
-  @override
-  bool operator ==(Object other) =>
-      other is Pair && other.first == first && other.second == second;
-}
-
 bool startsWithAny(String str, List<String> prefixes) =>
     prefixes.any(str.startsWith);