title: define two dimensional array in c# with string indexes
body: <p>How can I define something like this in c#:</p>
  
  <pre><code>list["alpha","beta"] = value;
  </code></pre>
  
  <p>And I want to access values such as dictionary:</p>
  
  <pre><code>var item = list["alpha","beta"];
  </code></pre>