title: Google charts (web) how to add a linear 45 degree line
body: <p>I got scatter chart which is perfectly fine and I can add trend-lines  but I can't find a way just to add a 45 degree line that goes from (0,0) to (1,1) example image below:
  <a href="https://i.stack.imgur.com/u7YPf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/u7YPf.png" alt="enter image description here"></a></p>
  
  <p>IS there any way to add a line like that to a google chart through it's web API?</p>