title: argparse options syntax for command line interface
body: <p>I am creating a project that generates some kind of code project structure, with base
  folders and files.</p>
  <p>My project it's currently using <code>argparse</code> for reading console input, but I am struggling
  with the syntax.</p>
  <p>I want to provide the user the following syntax:</p>
  <p><code>./my_executable new &lt;project_name&gt;</code></p>
  <p>Where there's an optional argument that it's <code>new</code>, and if it's provided, it should only accept one value for <code>project_name</code>.</p>
  <p>What w'd be the correct <code>argparse.add_argument()</code> syntax to achieve this?</p>