anchor.diff:    final Identifier identifier;
   
     VariableReference(this.identifier);
  +  VariableReference.forString(String name) : this(new Identifier(name));
   
     @override
     String toString() => "VariableReference(${identifier})";
  
positive.code: 
    bool get isSimpleString => components.every((x) => x is String);
    String asSimpleString() => components.join();
  }
  
  class NativeCode extends Expression {
  
negative.code: 
    bool get isTrue => value == true;
    bool get isFalse => value == false;
  
    BooleanLiteral negate() => new BooleanLiteral(!value);
  }
  
  class NamespaceBlock extends Statement {
  