compiler need support unary operation of in(de)crement or all of it should have syntax error.I have found many user have confused about it(such as:https://stackoverflow.com/questions/2632677/python-integer-incrementing-with). Of course, it is a big change of grammar and it need core developer team to make decision.

If core developer team support it, i will try my best to do it;)

The behavior is:

$ ./python
Python 3.8.0a4+ (heads/master:e225beb, Jun  4 2019, 00:35:07)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> i = 1;
>>> ++i
1
>>> i++
  File "<stdin>", line 1
    i++
      ^
SyntaxError: invalid syntax