On android:

root@generic_x86:/data/local/tmp # python
Python 3.6.0a0 (default:811ccdee6f87+, May  4 2016, 10:31:14) 
[GCC 4.9 20140827 (prerelease)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from _multiprocessing import sem_unlink
>>> sem_unlink('foo')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: [Errno 38] Function not implemented
>>>