 a
  tuple <code>T</code> whose <code>N</code>th element compares equal to <code>Key</code> is replaced
  with <code>NewTuple</code>, if there is such a tuple <code>T</code>.</td></tr>
<tr><td valign="top"><a href="#keytake-3">keytake/3</a></td><td>
  Searches the iterator of tuples <code>TupleIterator1</code> for a tuple whose
  <code>N</code>th element compares equal to <code>Key</code>.</td></tr>
<tr><td valign="top"><a href="#last-1">last/1</a></td><td>
  Returns the last element in <code>Iterator</code