an class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">0</span>, <span class="fl">1000</span><span class="op">)</span>, landscape <span class="op">=</span> <span class="st">"blank"</span><span class="op">)</span></span></span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="co"># it is possible to construct custom landscapes (islands, corridors, etc.)</span></span></span>
<span 