title: How to get child and grandchild elements from XML element?
body: <p>So, I have an XElement, that contains multiple child elements. I can successfully declare the XElement, and write it to a file:</p>
  
  <p>Test.project:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;project&gt;
      &lt;child&gt;
          &lt;grand-child1&gt;
              &lt;great-grand-child1&gt;Hello There!&lt;/great-grand-child1&gt;
              &lt;great-grand-child2&gt;Hello World!&lt;/great-grand-child2&gt;
          &lt;/grand-child1&gt;
          &lt;grand-child2&gt;Testing 123...&lt;/grand-child2&gt;
      &lt;/child&gt;
  &lt;/project&gt;
  </code></pre>
  
  <p>Then I'm trying to read from the file. I searched for ways to get child and grand-child nodes, and found I can use <code>XElement.XPathSelectElement()</code>. The problem is, Visual C# doesn't recognize <code>XPathSelectElement</code> as a method for an XElement. I've searched for usage examples for the method, and they all say to use <code>XElement.XPathSelectElement</code>.</p>
  
  <p>For example, I tried:</p>
  
  <pre><code>x_el = new XElement("project",
      new XElement("child",
          new XElement("grand-child", "Hello World!")
  );
  
  string get_string = x_el.XPathSelectElement("child/grand-child");
  </code></pre>
  
  <p>...but <code>XPathSelectElement</code> is not recognized. What am I doing wrong?</p>