title: Use of options/switches with "set" command
body: <p>I have come across a script (a section of it is shown below) which uses switches/options with <code>set</code> and <code>proc</code> in Tcl. Need help with the use and purpose of using the following constructs i.e switches and options with <code>set</code> and <code>proc</code> ...</p>
  
  <pre><code>set opt_args {
      -login_user        ANY
                         DEFAULT lab
      -login_passwd      ANY
                         DEFAULT lab 
  }
  
  set man_args {
      -ti           ANY
      -ra_name      ANY
      -r_name       ANY
  }
  
  aetest::script_init -mandatory_args $man_args \
          -optional_args $opt_args  -return_direct \
          -common_section_id last_test_id
  </code></pre>