Trailing Comma “Feature“ in Python

In short, make sure your python lines are "clean", cause some trailing symbols might not trigger syntax error, but results in the code doing things entirely different from your expectations:

>>> a = 2,
>>> a
(2,)

vs

>>> a = 2
>>> a
2

 trailing ',' would define a tuple instead of the intended data type and trigger a type error down the line.

source: class - member variable string gets treated as Tuple in Python - Stack Overflow

be careful! or you'd get this too: