Can this function be called pure?

I think this is a pure function as it abide by the rules to be a pure function.

1. It always return the same output.
2. It has no side effects.

But in a medium blog, they said that this is a impure function.

function addNumbers(){
  let num1 = 100;
  let num2 = 1;
  return num1 + num2;
}

addNumbers();