dentifier">columns</span>() <span class="ruby-ivar">@columns</span> <span class="ruby-operator">||=</span> []; <span class="ruby-keyword">end</span></pre>
            </div><!-- columns-source -->
            
          </div>

          

          
        </div><!-- columns-method -->

      
      </div><!-- public-class-method-details -->
    
      <div id="public-instance-method-details" class="method-section section">
        <h3 class="section-header">Public Instance Methods</h3>

      
        <d