It's called at different times so will return different values, which is important.

They meant something like "var n = Date.now".

However, there is no guarantee that this will work since it assumes that `this` isn't used by that function.

E.g. if you want to do something like that with console.log or document.querySelector, you have to use bind:

  var log = console.log.bind(console);
  var qs = document.querySelector.bind(document);

a = Date.now; b = a(); c = a();