title: Regex to match last character in string
body: <p>Suppose I have the following strings:
  <code>cat I</code> <code>cat II</code> <code>cat III</code> <code>dog I</code> <code>dog III</code> <code>bird I</code></p>
  
  <p>I would like to match all strings with a <code>I</code>, but NOT <code>II</code> or <code>III</code>. </p>
  
  <p>So the correct match would give me:</p>
  
  <pre><code>cat I
  dog I
  bird I
  </code></pre>
  
  <p>I had the thought of matching an <code>I</code> with no other character after it, but perhaps there is a more direct way. </p>
  
  <p>What would be the regex for such a pattern?</p>