os.path: Implement dirname(), basename().

os.path/os/path.py

@@ -28,6 +28,12 @@ def split(path):
         head = "/"
     return (head, r[1])
 
+def dirname(path):
+    return split(path)[0]
+
+def basename(path):
+    return split(path)[1]
+
 def exists(path):
     return os.access(path, os.F_OK)