title: Convert List<T> to HashTable
body: <p>I have a list:</p>
  
  <pre><code>public class tmp
  {
      public int Id;
      public string Name;
      public string LName;
      public decimal Index;
  }
  
  List&lt;tmp&gt; lst = GetSomeData();
  </code></pre>
  
  <p>I want to convert this list to HashTable, and I want to specify <code>Key</code> and <code>Value</code> in Extension Method Argument. For example I may want to <code>Key=Id</code> and <code>Value=Index</code> or <code>Key = Id + Index</code> and <code>Value = Name + LName</code>. How can I do this? </p>