title: get the file name from the file handle value
body: <p>let's say I have a filehandle. Is there a way for me to know the name of the file it is writing to?
  I.e., you usually use:</p>
  
  <pre><code>set fh [ open "fname" "w" ]
  </code></pre>
  
  <p>I want a proc that would have the output:</p>
  
  <pre><code>puts [ getFHFName $fh]
  &gt;fname
  </code></pre>
  
  <p>Any ideas?</p>