title: Specify range from -x to x
body: <p>I want my code to count up to a number n and then down to where it started, for example of n=4:</p>
  
  <p>1
  2
  3
  4
  3
  2
  1</p>
  
  <p>I've used range() to get from 1-4, and then reversed(range()) to get to 4-1, but they're two seperate blocks (and I'd get two 4's) and I'm sure there is a better and cleaner way. I've tried to specify the range from -n to n, but I honestly have no idea if I should use length, range or slices or whatever. I'm very new to programming.</p>