title: Ruby turn string into symbol
body: <p>I want to make a view helper that has a size argument ( e.g.   <code>func(size)</code>). The issue is that this size has to be used in the function as a symbol. For example, if I pass in <code>'medium'</code> into the <code>func</code> I need it to be converted to <code>:medium</code>.</p>
  
  <p>How do I do this?</p>