docs: def on_error_print_details(actual, expected):
      """
      Print text details in case of assertation failed errors.
  
      .. sourcecode:: python
  
          with on_error_print_details(actual_text, expected_text):
              ... # Do something
      """
      try:
          yield
      except Exception:
          diff = difflib.ndiff(expected.splitlines(), actual.splitlines())
          diff_text = u"\n".join(diff)
          print(u"DIFF (+ ACTUAL, - EXPECTED):\n{0}\n".format(diff_text))
          if DEBUG:
              print(u"expected:\n{0}\n".format(expected))
              print(u"actual:\n{0}".format(actual))
          raise