her elements of <code>Iterator</code>.</td></tr>
<tr><td valign="top"><a href="#next-1">next/1</a></td><td>
  Demand an element from <code>Iterator</code>.</td></tr>
<tr><td valign="top"><a href="#nth-2">nth/2</a></td><td>
  Returns the <code>N</code>th element of <code>Iterator</code>.</td></tr>
<tr><td valign="top"><a href="#nthtail-2">nthtail/2</a></td><td>
  Returns the <code>N</code>th tail of <code>Iterator1</code>, that is, the subiterator of
  <code>Iterator1</code> starting at <code>N</code>+1 and 