title: Regex to find words that start or end with a particular letter
body: <p>Write a function called <code>getWords(sentence, letter)</code> that takes in a sentence and a single letter, and returns a list of the words that start or end with this letter, but not both, regardless of the letter case. </p>
  
  <p>For example:</p>
  
  <pre><code>&gt;&gt;&gt; s = "The TART program runs on Tuesdays and Thursdays, but it does not start until next week."
  &gt;&gt;&gt; getWords(s, "t")
  ['The', 'Tuesdays', 'Thursdays', 'but', 'it', 'not', 'start', 'next']
  </code></pre>
  
  <p>My attempt: </p>
  
  <pre><code>regex = (r'[\w]*'+letter+r'[\w]*')
  return (re.findall(regex,sentence,re.I))
  </code></pre>
  
  <p>My Output:</p>
  
  <pre><code>['The', 'TART', 'Tuesdays', 'Thursdays', 'but', 'it', 'not', 'start', 'until', 'next']
  </code></pre>