title: Check whether string contains a full word
body: <p>Is there something in Ruby that returns true only if the string contains the whole word, in this case <code>'hello'</code>?</p>
  <p>I don't want the behavior of <code>include?</code> which returns true if only some characters within a word are present:</p>
  <pre><code>'hello whats up'.include? 'll'
  =&gt; true
  </code></pre>