diff --git a/Lib/doctest.py b/Lib/doctest.py
index 6927779..aad9dfe 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -167,6 +167,7 @@
 If you execute this very file, the examples above will be found and
 executed.
 """
+__docformat__ = 'reStructuredText en'
 
 __all__ = [
     'is_private',
@@ -330,6 +331,17 @@
         msg = '\n'.join([indent+l for l in msg[:-1].split('\n')])
         return '%s:\n%s\n' % (tag, msg)
 
+def _exception_traceback(exc_info):
+    """
+    Return a string containing a traceback message for the given
+    exc_info tuple (as returned by sys.exc_info()).
+    """
+    # Get a traceback message.
+    excout = StringIO()
+    exc_type, exc_val, exc_tb = exc_info
+    traceback.print_exception(exc_type, exc_val, exc_tb, file=excout)
+    return excout.getvalue()
+
 # Override some StringIO methods.
 class _SpoofOut(StringIO):
     def getvalue(self):
@@ -467,6 +479,11 @@
     """
     A class used to parse strings containing doctest examples.
     """
+    # This regular expression is used to find doctest examples in a
+    # string.  It defines three groups: `source` is the source code
+    # (including leading indentation and prompts); `indent` is the
+    # indentation of the first (PS1) line of the source code; and
+    # `want` is the expected output (including leading indentation).
     _EXAMPLE_RE = re.compile(r'''
         # Source consists of a PS1 line followed by zero or more PS2 lines.
         (?P<source>
@@ -479,7 +496,10 @@
                      .*$\n?       # But any other line
                   )*)
         ''', re.MULTILINE | re.VERBOSE)
-    _IS_BLANK_OR_COMMENT = re.compile('^[ ]*(#.*)?$').match
+
+    # This regular expression matcher checks if a given string is a
+    # blank line or contains a single comment.
+    _IS_BLANK_OR_COMMENT = re.compile(r'^[ ]*(#.*)?$').match
 
     def get_doctest(self, string, globs, name, filename, lineno):
         """
@@ -1125,7 +1145,7 @@
         Report that the given example failed.
         """
         # Print an error message.
-        out(self.__failure_header(test, example) +
+        out(self._failure_header(test, example) +
             self._checker.output_difference(example.want, got,
                                             self.optionflags))
 
@@ -1133,16 +1153,10 @@
         """
         Report that the given example raised an unexpected exception.
         """
-        # Get a traceback message.
-        excout = StringIO()
-        exc_type, exc_val, exc_tb = exc_info
-        traceback.print_exception(exc_type, exc_val, exc_tb, file=excout)
-        exception_tb = excout.getvalue()
-        # Print an error message.
-        out(self.__failure_header(test, example) +
-            _tag_msg("Exception raised", exception_tb))
+        out(self._failure_header(test, example) +
+            _tag_msg("Exception raised", _exception_traceback(exc_info)))
 
-    def __failure_header(self, test, example):
+    def _failure_header(self, test, example):
         s = (self.DIVIDER + "\n" +
              _tag_msg("Failure in example", example.source))
         if test.filename is None:
@@ -1256,10 +1270,10 @@
                                                    self.optionflags)):
                         # Is +exc_msg the right thing here??
                         self.report_success(out, test, example,
-                                            got+exc_hdr+exc_msg)
+                                       got+_exception_traceback(exc_info))
                     else:
                         self.report_failure(out, test, example,
-                                            got+exc_hdr+exc_msg)
+                                       got+_exception_traceback(exc_info))
                         failures += 1
 
         # Restore the option flags (in case they were modified)
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index 977ade7..c734cae 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -269,10 +269,10 @@
 
     >>> finder = doctest.DocTestFinder()
     >>> tests = finder.find(sample_func)
-    
+
     >>> print tests  # doctest: +ELLIPSIS
     [<DocTest sample_func from ...:12 (1 example)>]
-    
+
     >>> e = tests[0].examples[0]
     >>> (e.source, e.want, e.lineno)
     ('print sample_func(22)\n', '44\n', 3)
@@ -620,6 +620,7 @@
     ...     '''
     >>> test = doctest.DocTestFinder().find(f)[0]
     >>> doctest.DocTestRunner(verbose=False).run(test)
+    ... # doctest: +ELLIPSIS
     **********************************************************************
     Failure in example: raise ValueError, 'message'
     from line #1 of f
@@ -628,6 +629,7 @@
         ValueError: wrong message
     Got:
         Traceback (most recent call last):
+        ...
         ValueError: message
     (1, 1)
 
@@ -897,7 +899,7 @@
 
 Option directives affect only the example that they appear with; they
 do not change the options for surrounding examples:
-    
+
     >>> def f(x): r'''
     ...     >>> print range(10)       # Should fail: no ellipsis
     ...     [0, 1, ..., 9]
@@ -984,7 +986,7 @@
     >>> test = doctest.DocTestFinder().find(f)[0]
     >>> doctest.DocTestRunner(verbose=False).run(test)
     (0, 1)
-    
+
 For examples with multi-line source, the option directive may appear
 at the end of any line: