code: def test_empty_markup(self):
      res = convert_bsf("", "")
      self.assertEqual("", res)
  
file_path: stanza/stanza/tests/ner/test_bsf_2_beios.py
imports: import unittest
  from stanza.utils.datasets.ner.convert_bsf_to_beios import convert_bsf, parse_bsf, BsfInfo
  import pytest
label_desc: Use image node_id 1 for calling the TestBsf2Beios obj's underlying member method code with example usage: obj.test_empty_markup() without return types