the bits of the dynamic_bitset in the position range
<tt>[b*bits_per_block, (b+1)*bits_per_block)</tt>. For each
block number <tt>b</tt> with value <tt>bval</tt>, the bit
<tt>(bval &gt;&gt; i) &amp; 1</tt> corresponds to the bit at
position <tt>(b * bits_per_block + i)</tt> in the bitset (where
<tt>i</tt> goes through the range <tt>[0, bits_per_block)</tt>).
</li>
</ul>
<br />
<b>Requires:</b> <tt>BlockInputIterator</tt> must be either an
integral type or a model of <a href=
    "https://boost.org/sgi/stl/I