def compute_identity_hash(x):
    """RPython equivalent of object.__hash__(x).  This returns the
    so-called 'identity hash', which is the non-overridable default hash
    of Python.  Can be called for any RPython-level object that turns
    into a GC object, but not NULL.  The value will be different before
    and after translation (WARNING: this is a change with older RPythons!)
    """
    assert x is not None
    return object.__hash__(x)