title: drawing centered arcs in raphael js
body: <p>I need to draw concentric arcs of various sizes using raphael.js. I tried to understand the code behind <a href="https://dmitrybaranovskiy.github.io/raphael/polar-clock.html" rel="nofollow noreferrer">http://raphaeljs.com/polar-clock.html</a>, which is very similar to what I want, but, whithout comments, it is quite difficult to fathom.</p>
  
  <p>Ideally, I would need a function that creates a path that is at a given distance from some center point, starts at some angle and ends at some other angle.</p>