title: Lua - get indexOf string
body: <p>I am stuck with a problem in Lua to check whether the string value is not presented in another string.</p>
  
  <p>That's how I likely will do it in Javascript:</p>
  
  <pre><code>'my string'.indexOf('no-cache') === -1 // true
  </code></pre>
  
  <p>but in Lua I'm trying to use <code>string</code> module which gives me unexpected response:</p>
  
  <pre><code>string.find('my string', 'no-cache') -- nil, that's fine but..
  string.find('no-cache', 'no-cache') -- nil.. that's weird
  string.find('no-cache', 'no') -- 1, 2 here it's right.. strange..
  </code></pre>