class='id identifier rubyid_add'>add</span><span class='lparen'>(</span><span class='id identifier rubyid_balance'>balance</span><span class='rparen'>)</span>
    <span class='kw'>end</span>
  <span class='kw'>end</span>
<span class='kw'>end</span></pre>
    </td>
  </tr>
</table>
</div>
    
  </div>

  <div id="instance_method_details" class="method_details_list">
    <h2>Instance Method Details</h2>

    
      <div class="method_details first">
  <h3 class="signature first" id="add-instance_method">
  
