Failing test without any reason

Tell us what’s happening:

when I print my function output it shows well formated as asked by question
but still not showing ok test result
here below link please check, i have all things and spent very big time

Your code so far

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36.

Challenge: Arithmetic Formatter

Link to the challenge:

you have extra characters at the end of each line

but it not showing by print and return statement during my test
please explain it more

in the tests there is a diff output:

the lines starting with - is your code and those starting with + is what it should be, the lines with ? mark the difference between the two