code: def test_presto_expand_data_with_complex_row_columns_and_null_values(
      self,
  ):
      cols = [
          {
              "name": "row_column",
              "column_name": "row_column",
              "type": "ROW(NESTED_ROW ROW(NESTED_OBJ VARCHAR))",
              "is_dttm": False,
          }
      ]
      data = [
          {"row_column": '[["a"]]'},
          {"row_column": "[[null]]"},
          {"row_column": "[null]"},
          {"row_column": "null"},
      ]
      (
          actual_cols,
          actual_data,
          actual_expanded_cols,
      ) = PrestoEngineSpec.expand_data(cols, data)
      expected_cols = [
          {
              "name": "row_column",
              "column_name": "row_column",
              "type": "ROW(NESTED_ROW ROW(NESTED_OBJ VARCHAR))",
              "is_dttm": False,
          },
          {
              "name": "row_column.nested_row",
              "column_name": "row_column.nested_row",
              "type": "ROW(NESTED_OBJ VARCHAR)",
              "is_dttm": False,
          },
          {
              "name": "row_column.nested_row.nested_obj",
              "column_name": "row_column.nested_row.nested_obj",
              "type": "VARCHAR",
              "is_dttm": False,
          },
      ]
      expected_data = [
          {
              "row_column": [["a"]],
              "row_column.nested_row": ["a"],
              "row_column.nested_row.nested_obj": "a",
          },
          {
              "row_column": [[None]],
              "row_column.nested_row": [None],
              "row_column.nested_row.nested_obj": None,
          },
          {
              "row_column": [None],
              "row_column.nested_row": None,
              "row_column.nested_row.nested_obj": "",
          },
          {
              "row_column": None,
              "row_column.nested_row": "",
              "row_column.nested_row.nested_obj": "",
          },
      ]
  
      expected_expanded_cols = [
          {
              "name": "row_column.nested_row",
              "column_name": "row_column.nested_row",
              "type": "ROW(NESTED_OBJ VARCHAR)",
              "is_dttm": False,
          },
          {
              "name": "row_column.nested_row.nested_obj",
              "column_name": "row_column.nested_row.nested_obj",
              "type": "VARCHAR",
              "is_dttm": False,
          },
      ]
      self.assertEqual(actual_cols, expected_cols)
      self.assertEqual(actual_data, expected_data)
      self.assertEqual(actual_expanded_cols, expected_expanded_cols)
  
imports: from collections import namedtuple
  from textwrap import dedent
  from unittest import mock, skipUnless
  import pandas
  from flask.ctx import AppContext
  from sqlalchemy import types
  from sqlalchemy.sql import select
  from superset.db_engine_specs.presto import PrestoEngineSpec
  from superset.errors import ErrorLevel, SupersetError, SupersetErrorType
  from superset.sql_parse import ParsedQuery
  from superset.utils.database import get_example_database
  from tests.integration_tests.db_engine_specs.base_tests import TestDbEngineSpec
label_desc: Use image node_id 15 for calling the TestPrestoDbEngineSpec obj's underlying member method code with example usage: obj.test_presto_expand_data_with_complex_row_columns_and_null_values() without return types