title: Show the intersection of two curves
body: <p>If I have two plots defined by two different equations:</p>
  
  <pre><code>x = 0:0.01:30;
  y1 = x .^2 + 2;
  y2 = x .^3 ;
  </code></pre>
  
  <p>and I plot them as </p>
  
  <pre><code>plot(x, y1, x, y2);
  </code></pre>
  
  <p>How do I get a small ring around the point of intersection programatically (as in the following plot)?</p>
  
  <p><img src="https://i.stack.imgur.com/deVER.png" alt="enter image description here"></p>