title: Country name to ISO 3166-2 code
body: <p>I know how to convert an ISO 3166-2 code to the full English name, e.g. "US" to "United States" by using <code>RegionInfo</code>.</p>
  
  <p>However, how can I do the opposite, i.e. that takes "United States" and returns "US"?</p>