(maint): small fixes

[vladdoster]

• Use sys.exit() calls
• Use negative index -1 to get the last element of sequence
• Remove unnecessary use of comprehension
• Remove unnecessary f-string
• Fix incorrect f-string syntax
• Replace multiple == checks with in

To check if a variable is equal to one of many values, combine the values into a tuple and check if the variable is contained in it instead of checking for equality against each of the values. This is faster, less verbose, and more readable.

Signed-off-by: Vladislav Doster mvdoster@gmail.com

[doctormo]

These look like good changes to me.

[vladdoster]

@doctormo I don't have merge permissions.