Purpose of #!/usr/bin/python3

Question

I have noticed this in a couple of scripting languages, but in this example, I am using python. In many tutorials, they would start with #!/usr/bin/python3 on t

Answer 1

1. And this line is how.

2. It is ignored.

3. It will fail to run, and should be changed to point to the proper location. Or env should be used.

4. It will fail to run, and probably fail to run under a different version regardless.