Assignment expression in assert causes SyntaxError

Minimal case:
```
assert var := None
```

Error:
```
  File "<input>", line 1
    assert var := None
               ^
SyntaxError: invalid syntax
```

Workaround:
```
assert (var := None)
```

My use case:
```
my_dict = dict()
assert value := my_dict.get('key')
```

I believe this is by design, as is the same restriction on statement-level assignment expressions. And if requiring parens discourages the use of assignment expressions in asserts, I think that's a good thing.

Why not just use the workaround you've already identified?

if this is by design i'm fine with somebody closing this issue.

i've not found mention of such case in pep so i though it's not by design.
docs say `assert` just takes "expression" and "assignment expression" has "expression" in it's name.
https://docs.python.org/3/reference/simple_stmts.html#the-assert-statement

workaraund does not look as cool because of parentheses.

again, if this is "as intended" i'm fine with closing issue.

> assert var := None

It's good that this syntax is rejected: it looks like a typo (assert var == None). Moreover, it's part of of the PEP 572 design.
https://www.python.org/dev/peps/pep-0572/#exceptional-cases

Python works as expected, I suggest to close the issue as not a bug.

I'm going to close this, since I can't imagine this restriction being relaxed.

ok