title: Expression to find a specific length string surrounded by constants
body: <p>I do Regular Expressions so rarely that they always challenge me.  Even simple ones.</p>
  
  <p>How can I make a regular expression that will match all of these:</p>
  
  <pre><code> := 'abc'
   := 'xyz'
   := '2rs'
   := 'abe'
   := 'a2c'
  </code></pre>
  
  <p>Basically it starts with <code>:= '</code> and ends with <code>'</code> and has three values inside.   Could be numbers or chars.</p>