SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function JSONExtractString (children 1)
     ExpressionList (children 2)
      Literal \'["a"]\'
      Function toNullable (children 1)
       ExpressionList (children 1)
        Literal UInt64_1
