title: Is there a way to set up Clap or another arg lib to accept a plain '-' or '+' so that I can obtain argument groups without a named flag?
body: <p>I would like to be able to pass arguments using only the - and the + characters in the following format to clap or other arg lib.</p>
  
  <pre><code>program -i infile.txt -o outfile.txt - stra strb strc - strd stre strf + strg + strh stri
  </code></pre>
  
  <p>Where in the program I could then obtain vectors with the following groupings...</p>
  
  <pre><code>[stra, strb, strc]
  
  [strd, stre, strf]
  
  [strg]
  
  [strh, stri]
  </code></pre>
  
  <p>Is this possible in Clap or another rust arg library?  If so how can I accomplish it?   </p>