visit<R, C, CO extends C>  method 
Visit this node and possibly transform it.
Implementation
@override
R visit<R, C, CO extends C>(TemplateAstVisitor<R, C> visitor, CO context) =>
    visitor.visitAttr(this, context);Visit this node and possibly transform it.
@override
R visit<R, C, CO extends C>(TemplateAstVisitor<R, C> visitor, CO context) =>
    visitor.visitAttr(this, context);