title: How to build an array or collection
body: <p>I'd like to build a collection of several last highs and access all of them like I could in an array.
  How do I do that? My code looks like this:</p>
  
  <pre><code>var float lastHigh = 0
  if (highfound)
      lastHigh := high
  </code></pre>
  
  <p>Now I try this:</p>
  
  <pre><code>x := lastHigh[3]
  </code></pre>
  
  <p>... but x is only the LAST lastHigh value then (like it would be lastHigh[1]).
  So lastHigh is just a "flat" variable, right? How can I collect more than one last high?</p>