Answer 1

There's no such thing as a best line of code that one would normally use.

The idea doesn't really make sense.

It's like asking what's your best sentence to use when writing a research paper.

Answer 2

Open ended.

https://www.sololearn.com/discuss/1316935/?ref=app

Answer 3

What Avinesh said.

And I guess I am a very big fan of Python's comprehensions.

Answer 4

you mean like onliners or things that are often used?

Answer 5

Um...
i++;

Most often used, but probably doesn't help you much.