t;/tr&gt;&quot;</span>
      <span class="ruby-identifier">list_array</span>[<span class="ruby-identifier">i</span>] = <span class="ruby-identifier">str</span>
      <span class="ruby-identifier">i</span> <span class="ruby-operator">+=</span> <span class="ruby-value">1</span>
    <span class="ruby-keyword">end</span>
  <span class="ruby-keyword">end</span>   
  <span class="ruby-keyword">return</span> <span class="ruby-identifier">list_array</span>.<span class="ruby-identifier">join</span>(<span class="ruby