But I found a real bug to use a tuple with a comma.

Python3 recognized "abc", expression as tuple of one element.
But type() and len() recognize "abc", expression as "abc" string.
So now, I found a real bug.

I'll show you below sentences.

>>> "abc",
('abc',)
>>> obj = "abc",
>>> obj
('abc',)
>>> type(obj)
<class 'tuple'>
>>> len(("abc",))
1
>>> len(obj)
1

>>> type("abc",)
<class 'str'>
>>> len("abc",)
3