title: How to convert interface{} to string?
body: <p>I'm using <a href="http://docopt.org/">docopt</a> to parse command-line arguments. This works, and it results in a map, such as</p>
  
  <pre><code>map[&lt;host&gt;:www.google.de &lt;port&gt;:80 --help:false --version:false]
  </code></pre>
  
  <p>Now I would like to concatenate the <code>host</code> and the <code>port</code> value to a string with a colon in-between the two values. Basically, something such as:</p>
  
  <pre><code>host := arguments["&lt;host&gt;"] + ":" + arguments["&lt;port&gt;"]
  </code></pre>
  
  <p>Unfortunately, this doesn't work, as I get the error message:</p>
  
  <blockquote>
    <p>invalid operation: arguments[""] + ":" (mismatched types interface {} and string)</p>
  </blockquote>
  
  <p>So obviously I need to convert the value that I get from the map (which is just <code>interface{}</code>, so it can be anything) to a string. Now my question is, how do I do that?</p>