code: def test_ratio_for_null_seqn(self):
      # Check clearing of SF bug 763023
      s = difflib.SequenceMatcher(None, [], [])
      self.assertEqual(s.ratio(), 1)
      self.assertEqual(s.quick_ratio(), 1)
      self.assertEqual(s.real_quick_ratio(), 1)
  
imports: import difflib
  from test.support import findfile
  import unittest
  import doctest
  import sys
label_desc: Use image node_id 1 for calling the TestSFbugs obj's underlying member method code with example usage: obj.test_ratio_for_null_seqn() without return types