title: Regex pattern not work like expect
body: <p>I have pattern </p>
  
  <pre><code>/[^!]!(\z|[^!])/
  </code></pre>
  
  <p>And i have string: 
  "My string here!"</p>
  
  <p>i need check if string have 1 exclamation (but not !! or !!!)</p>