def _isNULL(obj):
    '''Prevent asizeof(all=True, ...) crash.

       Sizing gc.get_objects() crashes in Pythonista3 with
       Python 3.5.1 on iOS due to 1-tuple (<Null>,) object.
    '''
    return isinstance(obj, tuple) and len(obj) == 1 \
                                  and repr(obj) == '(<NULL>,)'
Prevent asizeof(all=True, ...) crash.

       Sizing gc.get_objects() crashes in Pythonista3 with
       Python 3.5.1 on iOS due to 1-tuple (<Null>,) object.
    
recipes/Python/546530_Size_of_Python_objects_revised/recipe-546530.py