title: Assert that text does not exist in SeleniumBase
body: <p>I am using SeleniumBase to test a website. My text removes an React element by clicking on the cross, and after I would like to verify that some text that was previously in the element doesn't exist any longer.</p>
  <p>Below is the code to click to remove the element, and assert that some text appears on the page. I would like to know if there is a way to do something like <code>self.assert_not_text(&quot;some text&quot;)</code> instead.</p>
  <pre><code>        self.click_xpath(
              f&quot;&quot;&quot;//*[@class='ant-select-selection-item-content' and text()='{common_issue}']/
              ../*[@class='ant-select-selection-item-remove']&quot;&quot;&quot;
          )
          self.assert_text(&quot;Some text&quot;)
  </code></pre>