SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function JSONExtract (children 1)
     ExpressionList (children 3)
      Literal \'{"a": {"c": "hello"}, "b": {"d": "world"}}\'
      Literal \'a\'
      Literal \'Map(String, String)\'