title: How can I change the case of a hash key?
body: <p>I am writing a script which is likely to be modified by users. Currently I am storing the configuration settings inside the script. It exists in the form of a hash-of-hashes.</p>
  
  <p>I would like to guard against people accidentally using lowercase characters in the hash keys, because that will break my script.</p>
  
  <p>It would be simple to inspect the hash keys and merely issue warnings for any keys with lowercase characters, but I would rather fix the case sensitivity automatically.</p>
  
  <p>In other words, I want to convert all the hash keys in the top-level hash to uppercase.</p>