DescribeQuery (children 1)
 TableExpression (children 1)
  Subquery (children 1)
   SelectWithUnionQuery (children 1)
    ExpressionList (children 1)
     SelectQuery (children 1)
      ExpressionList (children 3)
       Function CAST (alias a) (children 1)
        ExpressionList (children 2)
         Function tuple (children 1)
          ExpressionList (children 2)
           Literal UInt64_1
           Literal \'Value\'
         Literal \'Tuple (id UInt64, value String)\'
       Identifier a.id
       Identifier a.value
