SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Identifier json.a
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Subquery (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 1)
           Function CAST (alias json) (children 1)
            ExpressionList (children 2)
             Literal \'{"a" : 42}\'
             Literal \'JSON(a UInt32)\'
