+mimetypes = None
+
+def _guess_extension(ctype):
+ global mimetypes
+ if mimetypes is None:
+ import mimetypes
+ mimetypes.init()
+ user_mime_type = os.path.expanduser('~/.mime.types')
+ if os.path.exists(user_mime_type):
+ mimetypes._db.read(user_mime_type)
+ return mimetypes.guess_extension(ctype)
+