upleIterator1</code> for a tuple whose
  <code>N</code>th element compares equal to <code>Key</code>. Returns
  <code>{value, Tuple, TupleIterator2}</code> if such a tuple is found,
  otherwise <code>false</code>.  <code>TupleIterator2</code> is a copy of <code>TupleIterator1</code>
  where the first occurrence of <code>Tuple</code> has been removed.</p>
 
  Evaluates <code>TupleIterator1</code> until a match is found. Iterating over
  <code>TupleIterator2</code> will evaluate the same elements again. If no