)-&gt;nullable();
            $table-&gt;string(<span class="hljs-string">'vol_2'</span>)-&gt;nullable();
            $table-&gt;string(<span class="hljs-string">'vol_3'</span>)-&gt;nullable();
            $table-&gt;string(<span class="hljs-string">'door_1'</span>)-&gt;nullable();
            $table-&gt;string(<span class="hljs-string">'door_2'</span>)-&gt;nullable();
            $table-&gt;string(<span class="hljs-string">'door_3'</span>)-&gt;nullable();
            $table-&gt;string(<span class="hljs-str