SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 5)
    Identifier a
    Identifier b
    Function firstNonDefault (alias result1) (children 1)
     ExpressionList (children 3)
      Literal UInt64_42
      Identifier a
      Identifier b
    Function firstNonDefault (alias result2) (children 1)
     ExpressionList (children 3)
      Literal UInt64_0
      Identifier a
      Identifier b
    Function firstNonDefault (alias result3) (children 1)
     ExpressionList (children 3)
      Literal NULL
      Identifier a
      Identifier b
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier test_first_truthy
   ExpressionList (children 1)
    OrderByElement (children 1)
     Identifier ALL
