title: In directives when bringing in data what does an equal sign mean?
body: <p>I thought an equal sign means two way binding? As in I'd bring in a value of a camelCased attribute to my directive. </p>
  
  <p>What does this = mean then? I'm looking over some more advanced code in a book</p>
  
  <pre><code>.directive('contentHandler', function () {
  return {
    scope: {
      feed: '=contentHandler',
      onChange: '&amp;'
    },
  </code></pre>
  
  <p>I see it again here:</p>
  
  <pre><code>return {
    scope: {
      value: '=debug'
    },
  </code></pre>
  
  <p>Here is the html associated with the first one:</p>
  
  <pre><code>&lt;div content-handler="feed" on-change="onUpdate(element, action)"&gt;
  </code></pre>