Fix a bug from the map->itertools.imap conversion.

Lib/pydoc.py

@@ -986,8 +986,7 @@ class TextDoc(Doc):
     def indent(self, text, prefix='    '):
         """Indent text by prepending a given prefix to each line."""
         if not text: return ''
-        lines = text.split('\n')
-        lines = map(lambda line, prefix=prefix: prefix + line, lines)
+        lines = [prefix + line for line in text.split('\n')]
         if lines: lines[-1] = lines[-1].rstrip()
         return '\n'.join(lines)