list of 'magic methods' or builtin class methods... want to exclude those from dir output

[DG]

There is probably a better way to do this (please enlighten me, if you
know), but what I want to do is get a list of a class' attributes
minus whatever the 'builtin' methods are.  I would also like to do
this for instances of classes as well.  I don't want to use __dict__
because I want to get all of the attributes that have been added
throughout the inheritance tree, just not the builtin ones.

I was wondering if there is a function to return a list of these, so I
could perform a 'dir' on the object (class or instance) and filter out
the builtin attributes.  I know I could create my own list something
like
['__class__', '__delattr__', ..., '__weakref__'] and use that.  I
would see this being fragile to Python version differences as new ones
are added or taken away.

A more flexible way is to have the list be filled out dynamically by
creating a 'junk' class that inherits only from object and storing
it's dir() output into the filter list.  This is probably what I'll do
unless someone knows of a builtin function that will give me a
(version-safe) list.

Thanks!