title: Ruby: How to convert a string to boolean
body: <p>I have a value that will be one of four things: boolean true, boolean false, the string "true", or the string "false".  I want to convert the string to a boolean if it is a string, otherwise leave it unmodified.  In other words:</p>
  
  <p>"true" should become true</p>
  
  <p>"false" should become false</p>
  
  <p>true should stay true</p>
  
  <p>false should stay false</p>