diff --git a/CHANGELOG.md b/CHANGELOG.md
index e124b45..b0e267c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,10 +3,10 @@
   - `UndefinedError` exception
   - `UndefinedFactory` typedef
   - `Environment`:
-    - `Environment({undefined})` argument
-    - `undefined` field
+    - `Environment({UndefinedFactory undefined})` argument
+    - `UndefinedFactory undefined` field
   - `Template`:
-    - `Template({undefined})` argument
+    - `Template({UndefinedFactory undefined})` argument
   - Filters:
     - `null` (`none` alias)
 
diff --git a/README.md b/README.md
index 8b82866..92ca039 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,22 @@ See also examples with [conduit][conduit_example] and
   - `stream` method
 - Relative template paths
 - Async Support
+- Template Inheritance
+  - Super Blocks
+    - `{{ super.super() }}`
+- List of Control Structures
+  - Extends
+    - Execute non-`block` statements and expressions
+      ```jinja
+      {% extends 'base.html' %}
+      {% set title = 'Index' %}
+      {% macro header() %}
+        <h1>{{ title }}</h1>
+      {% endmacro %}      ```
+      {% block body %}
+        {{ header() }}
+      {% endblock %}
+      ```
 - Expressions
   - Dart Methods and Properties
     - `!.`/`?.`
@@ -73,7 +89,6 @@ See also examples with [conduit][conduit_example] and
   - ...
 - List of Global Functions
   - `lipsum`
-  - `dict`
   - `cycler`
   - `joiner`
 - Extensions
@@ -165,6 +180,7 @@ See also examples with [conduit][conduit_example] and
     - `{{ string.toUpperCase() }}`
     - `{{ list.add(item) }}`
 - List of Global Functions
+  - ~~`dict`~~
   - `print`
   - `range`
   - `list`
diff --git a/lib/src/compiler.dart b/lib/src/compiler.dart
index 11ca430..08476c4 100644
--- a/lib/src/compiler.dart
+++ b/lib/src/compiler.dart
@@ -3,16 +3,18 @@ import 'package:jinja/src/nodes.dart';
 import 'package:jinja/src/visitor.dart';
 import 'package:meta/meta.dart';
 
+// TODO(renderer): Rename to `StringSinkRendererCompiler`
+// and move to `renderer.dart`. Add `ContextNode` for `ContextCallback`s.
 @doNotStore
 class RuntimeCompiler implements Visitor<void, Node> {
   RuntimeCompiler()
       : _imports = <String>{},
-        _macroses = <String>{},
+        _macros = <String>{},
         _inMacro = false;
 
   final Set<String> _imports;
 
-  final Set<String> _macroses;
+  final Set<String> _macros;
 
   bool _inMacro;
 
@@ -46,8 +48,8 @@ class RuntimeCompiler implements Visitor<void, Node> {
 
   @override
   Call visitCall(Call node, void context) {
-    // Modifies Template AST from `loop.cycle(first, second, *list)`
-    // to `loop['cycle']([first, second], list)`, which matches
+    // Modifies Template AST from `loop.cycle(first, second)`
+    // to `loop['cycle']([first, second])`, which matches
     // [LoopContext.cycle] definition.
     //
     // TODO(compiler): check name arguments
@@ -59,7 +61,7 @@ class RuntimeCompiler implements Visitor<void, Node> {
             : <Expression>[Array(values: calling.arguments)];
 
         return node.copyWith(
-          value: visitNode(node.value, context),
+          value: Item(key: Constant(value: 'cycle'), value: value),
           calling: Calling(arguments: visitNodes(arguments, context)),
         );
       }
@@ -94,7 +96,7 @@ class RuntimeCompiler implements Visitor<void, Node> {
         );
       }
 
-      if (_inMacro && name == 'caller' || _macroses.contains(name)) {
+      if (_inMacro && name == 'caller' || _macros.contains(name)) {
         var calling = visitNode<Calling>(node.calling, context);
         var arguments = calling.arguments;
         var keywords = calling.keywords;
@@ -344,7 +346,7 @@ class RuntimeCompiler implements Visitor<void, Node> {
   @override
   FromImport visitFromImport(FromImport node, void context) {
     for (var (name, alias) in node.names) {
-      _macroses.add(alias ?? name);
+      _macros.add(alias ?? name);
     }
 
     return node.copyWith(template: visitNode(node.template, context));
@@ -378,7 +380,7 @@ class RuntimeCompiler implements Visitor<void, Node> {
   @override
   Macro visitMacro(Macro node, void context) {
     _inMacro = true;
-    _macroses.add(node.name);
+    _macros.add(node.name);
 
     var positional = <Expression>[];
     var named = <(Expression, Expression)>[];
@@ -420,17 +422,29 @@ class RuntimeCompiler implements Visitor<void, Node> {
   }
 
   @override
-  Output visitOutput(Output node, void context) {
+  Node visitOutput(Output node, void context) {
+    if (node.nodes.isEmpty) {
+      return Data();
+    }
+
+    if (node.nodes.length == 1) {
+      return visitNode(node.nodes[0], context);
+    }
+
     return node.copyWith(nodes: visitNodes(node.nodes, context));
   }
 
   @override
   TemplateNode visitTemplateNode(TemplateNode node, void context) {
-    return node.copyWith(
-      blocks: visitNodes(node.blocks, context),
-      macros: visitNodes(node.macros, context),
-      body: visitNode(node.body, context),
-    );
+    var body = visitNode(node.body, context) as Node;
+    var blocks = <Block>[if (body is Block) body, ...body.findAll<Block>()];
+    var macros = <Macro>[if (body is Macro) body, ...body.findAll<Macro>()];
+
+    if (body is Output && body.nodes.first is Extends) {
+      body = body.nodes.first;
+    }
+
+    return node.copyWith(blocks: blocks, macros: macros, body: body);
   }
 
   @override
diff --git a/lib/src/environment.dart b/lib/src/environment.dart
index 0b5c921..d34cd65 100644
--- a/lib/src/environment.dart
+++ b/lib/src/environment.dart
@@ -342,10 +342,8 @@ base class Environment {
   }
 
   /// Parse the source code and return the AST node.
-  ///
-  /// This can be useful for debugging or to extract information from templates.
   Node parse(String source, {String? path}) {
-    return scan(lex(source), path: path);
+    return Parser(this, path: path).parse(source);
   }
 
   /// Load a template from a source string without using [loader].
@@ -564,7 +562,7 @@ base class Template {
   /// The global variables for this template.
   final Map<String, Object?> globals;
 
-  /// Template body node.
+  // @nodoc
   @internal
   final TemplateNode body;
 
diff --git a/lib/src/loop.dart b/lib/src/loop.dart
index b529809..b504e10 100644
--- a/lib/src/loop.dart
+++ b/lib/src/loop.dart
@@ -1,197 +1,5 @@
-final class LoopContext extends Iterable<Object?> {
-  LoopContext(this.values, this.depth0, this.recurse)
-      : length = values.length,
-        index0 = -1;
+@Deprecated('Use `package:jinja/src/runtime.dart` instead')
+library;
 
-  final List<Object?> values;
-
-  @override
-  final int length;
-
-  final int depth0;
-
-  final String Function(Object? data, [int depth]) recurse;
-
-  int index0;
-
-  @override
-  LoopIterator get iterator {
-    return LoopIterator(this);
-  }
-
-  int get index {
-    return index0 + 1;
-  }
-
-  int get depth {
-    return depth0 + 1;
-  }
-
-  int get revindex0 {
-    return length - index;
-  }
-
-  int get revindex {
-    return length - index0;
-  }
-
-  @override
-  bool get first {
-    return index0 == 0;
-  }
-
-  @override
-  bool get last {
-    return index == length;
-  }
-
-  Object? get next {
-    if (last) {
-      return null;
-    }
-
-    return values[index0 + 1];
-  }
-
-  Object? get prev {
-    if (first) {
-      return null;
-    }
-
-    return values[index0 - 1];
-  }
-
-  Object? operator [](String key) {
-    switch (key) {
-      case 'length':
-        return length;
-      case 'index0':
-        return index0;
-      case 'depth0':
-        return depth0;
-      case 'index':
-        return index;
-      case 'depth':
-        return depth;
-      case 'revindex0':
-        return revindex0;
-      case 'revindex':
-        return revindex;
-      case 'first':
-        return first;
-      case 'last':
-        return last;
-      case 'prev':
-      case 'previtem':
-        return prev;
-      case 'next':
-      case 'nextitem':
-        return next;
-      case 'call':
-        return call;
-      case 'cycle':
-        return cycle;
-      case 'changed':
-        return changed;
-      default:
-        var invocation = Invocation.getter(Symbol(key));
-        throw NoSuchMethodError.withInvocation(this, invocation);
-    }
-  }
-
-  String call(Object? data) {
-    return recurse(data, depth);
-  }
-
-  Object? cycle(Iterable<Object?> values) {
-    var list = values.toList();
-
-    if (list.isEmpty) {
-      // TODO(loop): update error
-      throw TypeError();
-    }
-
-    return list[index0 % list.length];
-  }
-
-  bool changed(Object? item) {
-    if (index0 == 0) {
-      return true;
-    }
-
-    if (item == prev) {
-      return false;
-    }
-
-    return true;
-  }
-}
-
-final class LoopIterator implements Iterator<Object?> {
-  LoopIterator(this.context);
-
-  final LoopContext context;
-
-  @override
-  Object? get current {
-    return context.values[context.index0];
-  }
-
-  @override
-  bool moveNext() {
-    if (context.index < context.length) {
-      context.index0 += 1;
-      return true;
-    }
-
-    return false;
-  }
-}
-
-final class Cycler extends Iterable<Object?> {
-  Cycler(Iterable<Object?> values)
-      : values = List<Object?>.of(values),
-        length = values.length,
-        index = 0;
-
-  final List<Object?> values;
-
-  @override
-  final int length;
-
-  int index;
-
-  Object? get current {
-    return values[index];
-  }
-
-  @override
-  Iterator<Object?> get iterator {
-    return CyclerIterator(this);
-  }
-
-  Object? next() {
-    var result = current;
-    index = (index + 1) % length;
-    return result;
-  }
-
-  void reset() {
-    index = 0;
-  }
-}
-
-final class CyclerIterator implements Iterator<Object?> {
-  CyclerIterator(this.cycler);
-
-  final Cycler cycler;
-
-  @override
-  Object? current;
-
-  @override
-  bool moveNext() {
-    current = cycler.next();
-    return true;
-  }
-}
+export 'package:jinja/src/runtime.dart'
+    show LoopContext, LoopIterator, Cycler, CyclerIterator;
diff --git a/lib/src/nodes.dart b/lib/src/nodes.dart
index a05b4b3..c333562 100644
--- a/lib/src/nodes.dart
+++ b/lib/src/nodes.dart
@@ -137,7 +137,7 @@ final class Output extends Node {
 }
 
 final class TemplateNode extends Node {
-  const TemplateNode({
+  TemplateNode({
     this.blocks = const <Block>[],
     this.macros = const <Macro>[],
     required this.body,
@@ -169,14 +169,6 @@ final class TemplateNode extends Node {
 
   @override
   Iterable<T> findAll<T extends Node>() sync* {
-    for (var block in blocks) {
-      if (block case T block) {
-        yield block;
-      }
-
-      yield* block.findAll<T>();
-    }
-
     if (body case T body) {
       yield body;
     }
diff --git a/lib/src/nodes/statements.dart b/lib/src/nodes/statements.dart
index edc5f77..8948ffb 100644
--- a/lib/src/nodes/statements.dart
+++ b/lib/src/nodes/statements.dart
@@ -1,6 +1,6 @@
 part of '../nodes.dart';
 
-abstract class ImportContext {
+abstract interface class ImportContext {
   bool get withContext;
 }
 
diff --git a/lib/src/optimizer.dart b/lib/src/optimizer.dart
index 30b9d9d..7137e08 100644
--- a/lib/src/optimizer.dart
+++ b/lib/src/optimizer.dart
@@ -413,10 +413,7 @@ class Optimizer implements Visitor<Context, Node> {
 
   @override
   TemplateNode visitTemplateNode(TemplateNode node, Context context) {
-    return node.copyWith(
-      blocks: visitNodes<Block>(node.blocks, context),
-      body: visitNode<Node>(node.body, context),
-    );
+    return node.copyWith(body: visitNode<Node>(node.body, context));
   }
 
   @override
diff --git a/lib/src/parser.dart b/lib/src/parser.dart
index 96734b9..6490080 100644
--- a/lib/src/parser.dart
+++ b/lib/src/parser.dart
@@ -9,7 +9,7 @@ final class Parser {
   Parser(this.environment, {this.path})
       : endTokensStack = <List<(String, String?)>>[],
         tagStack = <String>[],
-        blocks = <Block>[];
+        blocks = <String>{};
 
   final Environment environment;
 
@@ -19,7 +19,7 @@ final class Parser {
 
   final List<String> tagStack;
 
-  final List<Block> blocks;
+  final Set<String> blocks;
 
   Extends? extendsNode;
 
@@ -322,7 +322,7 @@ final class Parser {
     var token = reader.next();
     var name = reader.expect('name');
 
-    if (blocks.any((block) => block.name == name.value)) {
+    if (!blocks.add(name.value)) {
       fail("Block '${name.value}' defined twice.", reader.current.line);
     }
 
@@ -350,15 +350,12 @@ final class Parser {
       reader.next();
     }
 
-    var block = Block(
+    return Block(
       name: name.value,
       scoped: scoped,
       required: required,
       body: body,
     );
-
-    blocks.add(block);
-    return block;
   }
 
   Extends parseExtends(TokenReader reader) {
@@ -1319,20 +1316,7 @@ final class Parser {
   Node scan(Iterable<Token> tokens) {
     var reader = TokenReader(tokens);
     var nodes = subParse(reader);
-
-    if (extendsNode case var extendsNode?) {
-      nodes = <Node>[extendsNode];
-    }
-
-    if (blocks.isEmpty) {
-      if (nodes.length == 1) {
-        return nodes.first;
-      }
-
-      return Output(nodes: nodes);
-    }
-
-    return TemplateNode(blocks: blocks.toList(), body: Output(nodes: nodes));
+    return Output(nodes: nodes);
   }
 
   List<Node> subParse(
@@ -1397,6 +1381,6 @@ final class Parser {
 
   Node parse(String template) {
     var tokens = environment.lex(template, path: path);
-    return scan(tokens);
+    return TemplateNode(body: scan(tokens));
   }
 }
diff --git a/lib/src/renderer.dart b/lib/src/renderer.dart
index ca0a9e3..24a0fba 100644
--- a/lib/src/renderer.dart
+++ b/lib/src/renderer.dart
@@ -2,7 +2,6 @@ import 'dart:math' as math;
 
 import 'package:jinja/src/environment.dart';
 import 'package:jinja/src/exceptions.dart';
-import 'package:jinja/src/loop.dart';
 import 'package:jinja/src/nodes.dart';
 import 'package:jinja/src/runtime.dart';
 import 'package:jinja/src/tests.dart';
@@ -19,13 +18,6 @@ abstract base class RenderContext extends Context {
     super.data,
   });
 
-  @override
-  RenderContext derived({String? template, Map<String, Object?>? data});
-
-  Object? finalize(Object? object) {
-    return environment.finalize(this, object);
-  }
-
   void assignTargets(Object? target, Object? current) {
     if (target is String) {
       set(target, current);
@@ -46,15 +38,22 @@ abstract base class RenderContext extends Context {
     } else if (target is NamespaceValue) {
       var value = resolve(target.name);
 
-      if (value is Namespace) {
-        value[target.item] = current;
-      } else {
-        throw TemplateRuntimeError('Non-namespace object');
+      if (value is! Namespace) {
+        throw TemplateRuntimeError('Non-namespace object.');
       }
+
+      value[target.item] = current;
     } else {
       throw TypeError();
     }
   }
+
+  @override
+  RenderContext derived({String? template, Map<String, Object?>? data});
+
+  Object? finalize(Object? object) {
+    return environment.finalize(this, object);
+  }
 }
 
 base class StringSinkRenderContext extends RenderContext {
@@ -87,7 +86,7 @@ base class StringSinkRenderContext extends RenderContext {
     return StringSinkRenderContext(
       environment,
       sink ?? this.sink,
-      template: template,
+      template: template ?? this.template,
       blocks: blocks,
       parent: parent,
       data: data,
@@ -105,11 +104,11 @@ base class StringSinkRenderer
   const StringSinkRenderer();
 
   Map<String, Object?> getDataForTargets(Object? targets, Object? current) {
-    if (targets case String string) {
-      return <String, Object?>{string: current};
+    if (targets is String) {
+      return <String, Object?>{targets: current};
     }
 
-    if (targets case List<Object?> targets) {
+    if (targets is List<Object?>) {
       var names = targets.cast<String>();
       var values = list(current);
 
@@ -140,8 +139,8 @@ base class StringSinkRenderer
     String macro(List<Object?> positional, Map<Object?, Object?> named) {
       var buffer = StringBuffer();
       var derived = context.derived(sink: buffer);
-      var index = 0;
 
+      var index = 0;
       var length = node.positional.length;
 
       for (; index < length; index += 1) {
@@ -258,7 +257,7 @@ base class StringSinkRenderer
       buffer.write(value.accept(this, context));
     }
 
-    return '$buffer';
+    return buffer.toString();
   }
 
   @override
@@ -387,7 +386,7 @@ base class StringSinkRenderer
     var derived = context.derived(sink: buffer);
     node.body.accept(this, derived);
 
-    Object? value = '$buffer';
+    Object? value = buffer.toString();
 
     var filters = node.filters;
 
@@ -448,7 +447,7 @@ base class StringSinkRenderer
     var derived = context.derived(sink: buffer);
     node.body.accept(this, derived);
 
-    Object? value = '$buffer';
+    Object? value = buffer.toString();
 
     for (var Filter(name: name, calling: calling) in node.filters) {
       var (positional, named) = calling.accept(this, context) as Parameters;
@@ -482,6 +481,7 @@ base class StringSinkRenderer
           orElse.accept(this, context);
         }
 
+        // Empty string prevents calling `finalize` on `null`.
         return '';
       }
 
@@ -510,6 +510,7 @@ base class StringSinkRenderer
         node.body.accept(this, forContext);
       }
 
+      // Empty string prevents calling `finalize` on `null`.
       return '';
     }
 
@@ -643,35 +644,57 @@ base class StringSinkRenderer
 
   @override
   void visitTemplateNode(TemplateNode node, StringSinkRenderContext context) {
+    // TODO(renderer): add `TemplateReference`
     var self = Namespace();
 
     for (var block in node.blocks) {
+      var blockName = block.name;
+
+      // TODO(compiler): switch to `ContextCallback`
       String render() {
-        var blocks = context.blocks[block.name];
+        var blocks = context.blocks[blockName];
 
-        if (blocks == null || blocks.isEmpty) {
-          throw UndefinedError("Block '${block.name}' is not defined.");
+        if (blocks == null) {
+          throw UndefinedError("Block '$blockName' is not defined.");
         }
 
-        blocks.last(context);
+        // TODO(renderer): check if empty
+        blocks[0](context);
         return '';
       }
 
-      self[block.name] = render;
+      self[blockName] = render;
 
-      var blocks = context.blocks[block.name] ??= <ContextCallback>[];
+      var blocks = context.blocks[blockName] ??= <ContextCallback>[];
 
       if (block.required) {
-        String callback(Context context) {
+        Never callback(Context context) {
           throw TemplateRuntimeError(
               "Required block '${block.name}' not found.");
         }
 
         blocks.add(callback);
       } else {
-        String callback(Context context) {
+        var parentIndex = blocks.length + 1;
+
+        void callback(Context context) {
+          var current = context.get('super');
+
+          // TODO(renderer): add `BlockReference`
+          String parent() {
+            var blocks = context.blocks[blockName]!;
+
+            if (parentIndex >= blocks.length) {
+              throw TemplateRuntimeError("Super block '$blockName' not found.");
+            }
+
+            blocks[parentIndex](context);
+            return '';
+          }
+
+          context.set('super', parent);
           block.body.accept(this, context);
-          return '';
+          context.set('super', current);
         }
 
         blocks.add(callback);
diff --git a/lib/src/runtime.dart b/lib/src/runtime.dart
index 07ac9a9..88979d0 100644
--- a/lib/src/runtime.dart
+++ b/lib/src/runtime.dart
@@ -70,7 +70,11 @@ base class Context {
       return parent[name];
     }
 
-    return environment.undefined(name, template);
+    return undefined(name, template);
+  }
+
+  Object? get(String key) {
+    return context[key];
   }
 
   void set(String key, Object? value) {
@@ -115,6 +119,204 @@ base class Context {
   }
 }
 
+final class LoopContext extends Iterable<Object?> {
+  LoopContext(this.values, this.depth0, this.recurse)
+      : length = values.length,
+        index0 = -1;
+
+  final List<Object?> values;
+
+  @override
+  final int length;
+
+  final int depth0;
+
+  final String Function(Object? data, [int depth]) recurse;
+
+  int index0;
+
+  @override
+  LoopIterator get iterator {
+    return LoopIterator(this);
+  }
+
+  int get index {
+    return index0 + 1;
+  }
+
+  int get depth {
+    return depth0 + 1;
+  }
+
+  int get revindex0 {
+    return length - index;
+  }
+
+  int get revindex {
+    return length - index0;
+  }
+
+  @override
+  bool get first {
+    return index0 == 0;
+  }
+
+  @override
+  bool get last {
+    return index == length;
+  }
+
+  Object? get next {
+    if (last) {
+      return null;
+    }
+
+    return values[index0 + 1];
+  }
+
+  Object? get prev {
+    if (first) {
+      return null;
+    }
+
+    return values[index0 - 1];
+  }
+
+  Object? operator [](String key) {
+    switch (key) {
+      case 'length':
+        return length;
+      case 'index0':
+        return index0;
+      case 'depth0':
+        return depth0;
+      case 'index':
+        return index;
+      case 'depth':
+        return depth;
+      case 'revindex0':
+        return revindex0;
+      case 'revindex':
+        return revindex;
+      case 'first':
+        return first;
+      case 'last':
+        return last;
+      case 'prev':
+      case 'previtem':
+        return prev;
+      case 'next':
+      case 'nextitem':
+        return next;
+      case 'call':
+        return call;
+      case 'cycle':
+        return cycle;
+      case 'changed':
+        return changed;
+      default:
+        var invocation = Invocation.getter(Symbol(key));
+        throw NoSuchMethodError.withInvocation(this, invocation);
+    }
+  }
+
+  String call(Object? data) {
+    return recurse(data, depth);
+  }
+
+  Object? cycle(Iterable<Object?> values) {
+    var list = values.toList();
+
+    if (list.isEmpty) {
+      // TODO(loop): update error
+      throw TypeError();
+    }
+
+    return list[index0 % list.length];
+  }
+
+  bool changed(Object? item) {
+    if (index0 == 0) {
+      return true;
+    }
+
+    if (item == prev) {
+      return false;
+    }
+
+    return true;
+  }
+}
+
+final class LoopIterator implements Iterator<Object?> {
+  LoopIterator(this.context);
+
+  final LoopContext context;
+
+  @override
+  Object? get current {
+    return context.values[context.index0];
+  }
+
+  @override
+  bool moveNext() {
+    if (context.index < context.length) {
+      context.index0 += 1;
+      return true;
+    }
+
+    return false;
+  }
+}
+
+final class Cycler extends Iterable<Object?> {
+  Cycler(Iterable<Object?> values)
+      : values = List<Object?>.of(values),
+        length = values.length,
+        index = 0;
+
+  final List<Object?> values;
+
+  @override
+  final int length;
+
+  int index;
+
+  Object? get current {
+    return values[index];
+  }
+
+  @override
+  Iterator<Object?> get iterator {
+    return CyclerIterator(this);
+  }
+
+  Object? next() {
+    var result = current;
+    index = (index + 1) % length;
+    return result;
+  }
+
+  void reset() {
+    index = 0;
+  }
+}
+
+final class CyclerIterator implements Iterator<Object?> {
+  CyclerIterator(this.cycler);
+
+  final Cycler cycler;
+
+  @override
+  Object? current;
+
+  @override
+  bool moveNext() {
+    current = cycler.next();
+    return true;
+  }
+}
+
 base class Namespace {
   Namespace([Map<String, Object?>? data])
       : context = <String, Object?>{...?data};
diff --git a/lib/src/visitor.dart b/lib/src/visitor.dart
index b28918d..11ca044 100644
--- a/lib/src/visitor.dart
+++ b/lib/src/visitor.dart
@@ -87,183 +87,183 @@ class ThrowingVisitor<C, R> implements Visitor<C, R> {
 
   @override
   R visitArray(Array node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitAttribute(Attribute node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitCall(Call node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitCalling(Calling node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitCompare(Compare node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitConcat(Concat node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitCondition(Condition node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitConstant(Constant node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitDict(Dict node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitFilter(Filter node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitItem(Item node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitLogical(Logical node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitName(Name node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitNamespaceRef(NamespaceRef node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitScalar(Scalar node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitTest(Test node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitTuple(Tuple node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitUnary(Unary node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   // Statements
 
   @override
   R visitAssign(Assign node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitAssignBlock(AssignBlock node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitBlock(Block node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitCallBlock(CallBlock node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitData(Data node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitDo(Do node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitExtends(Extends node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitFilterBlock(FilterBlock node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitFor(For node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitFromImport(FromImport node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitIf(If node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitImport(Import node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitInclude(Include node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitInterpolation(Interpolation node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitMacro(Macro node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitOutput(Output node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitTemplateNode(TemplateNode node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 
   @override
   R visitWith(With node, C context) {
-    throw UnimplementedError('$node');
+    throw UnimplementedError();
   }
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index db1ede8..a4dac83 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: jinja
-version: 0.6.1-dev.4
+version: 0.6.1-dev.5
 description: >-
   Jinja2 template engine for Dart.
   Variables, expressions, control structures and template inheritance.
diff --git a/test/api_test.dart b/test/api_test.dart
index f1b4f34..a6cec19 100644
--- a/test/api_test.dart
+++ b/test/api_test.dart
@@ -2,7 +2,6 @@
 library;
 
 import 'package:jinja/jinja.dart';
-import 'package:jinja/src/loop.dart';
 import 'package:jinja/src/runtime.dart';
 import 'package:test/test.dart';
 
diff --git a/test/statements/set_test.dart b/test/statements/set_test.dart
index 7a95936..bb3d66c 100644
--- a/test/statements/set_test.dart
+++ b/test/statements/set_test.dart
@@ -30,7 +30,7 @@ void main() {
       expect(
           () => tmpl.render({'foo': emptyMap}),
           throwsA(predicate<TemplateRuntimeError>(
-              (error) => error.message == 'Non-namespace object')));
+              (error) => error.message == 'Non-namespace object.')));
     });
 
     test('namespace redefined', () {
@@ -39,7 +39,7 @@ void main() {
       expect(
           () => tmpl.render({'namespace': () => emptyMap}),
           throwsA(predicate<TemplateRuntimeError>(
-              (error) => error.message == 'Non-namespace object')));
+              (error) => error.message == 'Non-namespace object.')));
     });
 
     test('namespace', () {
diff --git a/test/test.dart b/test/test.dart
deleted file mode 100644
index 8102a69..0000000
--- a/test/test.dart
+++ /dev/null
@@ -1,19 +0,0 @@
-// ignore_for_file: avoid_print
-
-import 'dart:convert';
-
-import 'package:jinja/jinja.dart';
-
-const Map<String, String> sources = <String, String>{
-  'include': '{% macro test(foo) %}[{{ foo }}]{% endmacro %}',
-};
-
-void main() {
-  var loader = MapLoader(sources);
-  var env = Environment(loader: loader);
-  var tmpl = env.fromString('''
-{% from "include" import test -%}
-{{ test("foo") }}''');
-  print(JsonEncoder.withIndent('  ').convert(env.getTemplate('include').body.toJson()));
-  print(tmpl.render());
-}