anchor.diff:    return null;
   }
   
  -/**
  - * Closurzes a method reflectively.
  - */
  +/// Closurzes a method reflectively.
   class Method /* implements Function */ {
     final InstanceMirror mirror;
     final Symbol symbol;
  
positive.code:   return false;
  }
  
  /**
   * Walks up the class hierarchy to find a method declaration with the given
   * [name].
   *
   * Note that it's not possible to tell if there's an implementation via
   * noSuchMethod().
   */
  DeclarationMirror getDeclaration(ClassMirror classMirror, Symbol name) {
    if (classMirror.declarations.containsKey(name)) {
      return classMirror.declarations[name];
  
negative.code: 
  import 'dart:mirrors';
  
  /// Returns the qualified name of [t].
  Symbol getTypeName(Type t) => reflectClass(t).qualifiedName;
  
  /// Returns true if [o] implements [type].
  bool implements(Object o, Type type) =>
      classImplements(reflect(o).type, reflectClass(type));
  
  /// Returns true if the class represented by [classMirror] implements the class
  /// represented by [interfaceMirror].
  bool classImplements(ClassMirror classMirror, ClassMirror interfaceMirror) {
    if (classMirror == null) return false;
    // TODO: change to comparing mirrors when dartbug.com/19781 is fixed
  