Question mark in variable and function names

[Andr? N?ss]

One thing I liked about Lisp was the ability to use the question mark
(and the exclamation mark) in function names. I found this
particularily useful when checking boolean properties of a object like
for example myObj.isContextSet. It just feels so much more natural to
write myObj.contextSet?

I also found it neat that destructive operations were clearly marked
with !.

Is there anything preventing this from being possible in Python?

One of the things I really love about Python is the way it feels when
I type it. It just comes completely natural to write "for foo in bar"
and then push the colon, all those curly braces on the other hand
always feel awkward.