title: Proper help for arguments
body: <p>Python optparse works very good when script usage is something like this</p>
  
  <pre><code>%prog [options] [args]
  </code></pre>
  
  <p>But I need to write help for script with 1 required argument, so usage will be like this</p>
  
  <pre><code>%prog action [options] [args]
  </code></pre>
  
  <p>You can see something similar when you use Subversion - its usage string is</p>
  
  <pre><code>svn &lt;subcommand&gt; [options] [args]
  </code></pre>
  
  <p>So my question is: is it possible to prepare help for required argument with optparse in the manner of Subversion? As a result I want to see help like this:</p>
  
  <pre><code>Usage: python myscript.py action [options] [args]
  
  Available actions:
    foo
    bar
  
  Options:
    --version             show program's version number and exit
    -h, --help            show this help message and exit
    -v, --verbose         Verbose mode. Output debug log to stdout.
  </code></pre>