l <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/pkg/bigparallelr/man/seq-dim.html" class="external-link">cols_along</a></span><span class="op">(</span><span class="va">X</span><span class="op">)</span>,</span>
<span>  k <span class="op">=</span> <span class="fl">10</span>,</span>
<span>  block.size <span class="op">=</span> <span class="fu"><a href="block_size.html">block_size</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/nrow.html" class="external