an> <span class="fu"><a href="https://rdrr.io/r/base/range.html">range</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/unlist.html">unlist</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/lapply.html">lapply</a></span><span class="op">(</span>
      <span class="va">xspline_points</span>,
      <span class="kw">function</span><span class="op">(</span><span class="va">pts</span><span class="op">)</span> <span class="fu"><a href="https://r