Ran into this today. If you forget to close parentheses as part of a call in the header of a for, with, or class statement (maybe others too?), the SyntaxError seems to indicate that you forgot a colon:

>>> for foo in bar(baz:
  File "<stdin>", line 1
    for foo in bar(baz:
                  ^
SyntaxError: expected ':'

It's not wrong, but could probably be improved. I personally find the pre-3.10 behavior more helpful:

>>> bar(baz:
  File "<stdin>", line 1
    for foo in bar(baz:
                      ^
SyntaxError: invalid syntax

Even better, though, would be a "smarter" error message like the existing ones we have for unclosed parentheses:

>>> bar(baz:
  File "<stdin>", line 1
    for foo in bar(baz:
                  ^
SyntaxError: '(' was never closed

@pablogsal