Interface Expression

interface Expression {
    arg?: CST.VariableRef | CST.Literal;
    attributes: Attribute[];
    braces: [Syntax<"{">] | [Syntax<"{">, Syntax<"}">];
    end: number;
    functionRef?: Junk | CST.FunctionRef;
    markup?: CST.Markup;
    start: number;
    type: "expression";
}