Code cleanup.

From PR review.

docs/shared/conf.py

@@ -25,7 +25,15 @@ import sys, os
 
 BASEDIR = os.path.dirname(os.path.abspath(__file__))
 
-add_base = lambda l: map(lambda x: os.path.join(BASEDIR, x), l)
+def add_base(paths):
+    """
+    Returns a list of paths relative to BASEDIR.
+
+    paths: a list of paths
+    """
+
+    return [os.path.join(BASEDIR, x) for x in paths]
+    
 
 
 # If extensions (or modules to document with autodoc) are in another directory,