final case classExpression(render: Predef.String) extends XQuery with Product with Serializable
final case classFlwor(bindingClauses: NonEmptyList[BindingClause], filterExpr: Predef.Option[XQuery], orderSpecs: IList[(XQuery, SortDirection)], orderIsStable: Predef.Boolean, resultExpr: XQuery) extends XQuery with Product with Serializable
final case classStep(render: Predef.String) extends XQuery with Product with Serializable