Too Long; Didn't Read
Python is now the third most popular programming language in the world, with a usage rate of 12.21%. Python programs are written in the functional language style which doesn’t avoid all I/O or all assignments; instead of that, they have a functional-looking interface but use non-functional functionality internally. Pure functions are just a function that does not have a side effect, and it returns the exact same thing every single time, you give it the same inputs, you call these functions with the same input, it always gives you the same output and it affects nothing else outside of it. Pure function is easier to reuse the same code in other contexts because functions do not depend on any external state or variable.