title: xpath logical operator precedence of AND and OR, without parenthesis
body: <p>I'm writing an xpath expression to achieve this:</p>
  
  <pre><code>//parent[(childA[contains(.,"foo")] or childB[contains(.,"foo")]) AND (childA[contains(.,"bar")] or childB[contains(.,"bar")])]
  </code></pre>
  
  <p>which is to select a parent whose children (childA or childB or both childA and childB together) contain both the strings "foo" and "bar".</p>
  
  <p>I'm not sure whether parenthesis before and after AND is correctly used. Can xpath have parenthesis like this?</p>
  
  <p>Thanks in advance!!</p>