title: Match an item to a list of items
body: <p>Let's say I want to group States into Regions. For instance, the Southwest Region might be: Texas, Oklahoma, Colorado, New Mexico, Utah, Arizona, Nevada.</p>
  
  <p>Somehow I need to create the list of states and define the region groupings. I also need to be able to lookup a region given the name of a state, something like <code>region_for('Texas')</code> which would return <code>'Southwest'</code>.</p>
  
  <p>What is the best, cleanest, "Ruby Way" to do something like this? I'd like to do it using plain 'ol ruby, no database or frameworks.</p>