def _findDescendantBreadth(acc, pred):
        """
        Internal function for locating one descendant. Called by L{findDescendant} to
        start the search.

        @param acc: Root accessible of the search
        @type acc: Accessibility.Accessible
        @param pred: Search predicate returning True if accessible matches the 
                        search criteria or False otherwise
        @type pred: callable
        @return: Matching node or None to keep searching
        @rtype: Accessibility.Accessible or None
        """
        for child in acc:
                try:
                        if pred(child): return child
                except Exception:
                        pass
        for child in acc:
                try:
                        ret = _findDescendantBreadth(child, pred)
                except Exception:
                        ret = None
                if ret is not None: return ret