FunctionToken

interface FunctionToken {
    "[ROOT]"?: AstStyleSheet | null;
    chi: Token[];
    parent?: any;
    typ:
        | FunctionTokenType
        | TimelineFunctionTokenType
        | TimingFunctionTokenType
        | UrlFunctionTokenType
        | ImageFunctionTokenType
        | PseudoClassFuncTokenType
        | ColorTokenType
        | GridTemplateFuncTokenType
        | MathFunctionTokenType
        | TransformFunctionTokenType
        | GeneralEnclosedFunctionTokenType
        | WildCardFunctionTokenType;
    val: string;
    [key: number]: string
    | undefined;
}