Can someone please explain what the last sentence in this paragraph from the docs means:

In general, you should not touch __init__. Instead use the _init method, which is called after an object is fetched or inserted. This method has the signature _init(self, id, connection=None, selectResults=None), though you may just want to use _init(self, *args, **kw). Note: don't forget to call SQLObject._init(self, *args, **kw) if you override the method!

I.e. when do I have to call SQLObject._init...when i override any _init?  I'm still getting my sea legs here.  :)