code: def test_customlabel(self):
      # Limited test of custom custom labeling
      tbl = SimpleTable(
          table1data, test1header, test1stubs, txt_fmt=txt_fmt1
      )
      tbl[1][1].data = np.nan
      tbl.label_cells(custom_labeller)
      # print([[c.datatype for c in row] for row in tbl])
      desired = """
  *****************************
  *       * header1 * header2 *
  *****************************
  * stub1 *    --   *       1 *
  * stub2 *    2.00 *       3 *
  *****************************
  """
      actual = "\n%s\n" % tbl.as_text(missing="--")
      assert_equal(actual, desired)
  
file_path: statsmodels/statsmodels/iolib/tests/test_table_econpy.py
imports: import numpy
  from numpy.testing import assert_equal
  from statsmodels.iolib.table import Cell, SimpleTable
  from statsmodels.iolib.table import default_latex_fmt
  from statsmodels.iolib.table import default_html_fmt
label_desc: Use image node_id 4 for calling the TestSimpleTable obj's underlying member method code with example usage: obj.test_customlabel() without return types