r1 with duplicated  
elements removed (preserving the order of the elements).</td></tr>
<tr><td valign="top"><a href="#uniq-2">uniq/2</a></td><td>  
Returns an iterator containing the elements of Iterator1 without the  
elements for which Fun returned duplicate values (preserving the  
order of the elements).</td></tr>
<tr><td valign="top"><a href="#unzip-1">unzip/1</a></td><td>
  "Unzips" a iterator of two-tuples into two iterators, where the
  first iterator contains the first element of each tuple, and t