in later/unittest/backport/mock.py [0:0]
def _check_and_set_parent(parent, value, name, new_name):
value = _extract_mock(value)
if not _is_instance_mock(value):
return False
if ((value._mock_name or value._mock_new_name) or
(value._mock_parent is not None) or
(value._mock_new_parent is not None)):
return False
_parent = parent
while _parent is not None:
# setting a mock (value) as a child or return value of itself
# should not modify the mock
if _parent is value:
return False
_parent = _parent._mock_new_parent
if new_name:
value._mock_new_parent = parent
value._mock_new_name = new_name
if name:
value._mock_parent = parent
value._mock_name = name
return True