def METHOD_NAME():
    """Test the ``cast_to_datetime64`` function.
    Setup:
        - String value representing a datetime
        - List value with a ``np.nan`` and string values.
        - pd.Series with datetime values.
    Output:
        - A single np.datetime64
        - A list of np.datetime64
        - A series of np.datetime64
    """
    # Setup
    string_value = '2021-02-02'
    list_value = [None, np.nan, '2021-02-02']
    series_value = pd.Series(['2021-02-02', None, pd.NaT])
    # Run
    string_out = cast_to_datetime64(string_value)
    list_out = cast_to_datetime64(list_value)
    series_out = cast_to_datetime64(series_value)
    # Assert
    expected_string_output = np.datetime64('2021-02-02')
    expected_series_output = pd.Series([
        np.datetime64('2021-02-02'),
        np.datetime64('NaT'),
        np.datetime64('NaT')
    ])
    expected_list_output = np.array([
        np.datetime64('NaT'),
        np.datetime64('NaT'),
        '2021-02-02'
    ], dtype='datetime64[ns]')
    np.testing.assert_array_equal(expected_list_output, list_out)
    pd.testing.assert_series_equal(expected_series_output, series_out)
    assert expected_string_output == string_out