code: def test_range_format_unified(self):
      # Per the diff spec at http://www.unix.org/single_unix_specification/
      spec = """\
             Each <range> field shall be of the form:
               %1d", <beginning line number>  if the range contains exactly one line,
             and:
              "%1d,%1d", <beginning line number>, <number of lines> otherwise.
             If a range is empty, its beginning line number shall be the number of
             the line just before the range, or 0 if the empty range starts the file.
          """
      fmt = difflib._format_range_unified
      self.assertEqual(fmt(3, 3), "3,0")
      self.assertEqual(fmt(3, 4), "4")
      self.assertEqual(fmt(3, 5), "4,2")
      self.assertEqual(fmt(3, 6), "4,3")
      self.assertEqual(fmt(0, 0), "0,0")
  
imports: import difflib
  from test.support import findfile
  import unittest
  import doctest
  import sys
label_desc: Use image node_id 3 for calling the TestOutputFormat obj's underlying member method code with example usage: obj.test_range_format_unified() without return types