title: finding and returning a string with a specified prefix
body: <p>I am close but I am not sure what to do with the restuling match object. If I do </p>
  
  <pre><code>p = re.search('[/@.* /]', str)
  </code></pre>
  
  <p>I'll get any words that start with @ and end up with a space. This is what I want. However this returns a Match object that I dont' know what to do with. What's the most computationally efficient way of finding and returning a string which is prefixed with a @?</p>
  
  <p>For example, </p>
  
  <pre><code>"Hi there @guy"
  </code></pre>
  
  <p>After doing the proper calculations, I would be returned </p>
  
  <pre><code>guy
  </code></pre>