code: def _check_1col(
      df: pd.DataFrame, col: str = "y", vals: Set[Union[int, str]] = {1}
  ) -> None:
      """Helper to check that 1 column has the same value and a case-insensitive matching name.
  
      We lower-case the names due to snowflake's tendency to capitalize things. This isn't ideal but it'll do for now.
      """
      df.columns = df.columns.str.lower()
      col = col.lower()
      assert isinstance(df, pd.DataFrame)
      assert df.shape == (len(vals), 1)
      assert df.columns.tolist() == [col]
      assert set(df[col]) == vals
  
imports: from __future__ import annotations
  import logging
  from typing import Set, Union
  import pandas
  import pytest
  from metricflow.dataflow.sql_table import SqlTable
  from metricflow.protocols.sql_client import SqlClient, SqlEngine
  from metricflow.random_id import random_id
  from metricflow.sql.sql_bind_parameters import SqlBindParameters
  from metricflow.test.compare_df import assert_dataframes_equal
  from metricflow.test.fixtures.setup_fixtures import MetricFlowTestSessionState
  from metricflow.test.fixtures.sql_clients.ddl_sql_client import SqlClientWithDDLMethods
label_desc: Use image node_id 3 for calling a global function with example usage: _check_1col(df, col, vals) without return types