16..66 'for _ ...     }': fn next<IntoIterator::IntoIter<()>>(&'? mut IntoIterator::IntoIter<()>) -> Option<<IntoIterator::IntoIter<()> as Iterator>::Item>
            16..66 'for _ ...     }': fn next<IntoIterator::IntoIter<()>>(&'? mut IntoIterator::IntoIter<()>) -> Option<<IntoIterator::IntoIter<()> as Iterator>::Item>