title: Lambda expression in ToDictionary
body: <p>To convert a list to a dictionary, we can do it easily with the follwing:</p>
  
  <pre><code>list.ToDictionary(v=&gt; v, v=&gt;true);
  </code></pre>
  
  <p>For the first parameter in <code>ToDictionary</code>, I can understand the first parameter is the element of the dictionary. But what is meant by <code>v=&gt; true</code>? </p>
  
  <p>The second parameter should be of the type <code>IEqualityComparer</code>. What purpose does this serve? How is <code>v=&gt; true</code> same as <code>IEqualityComparer</code>?</p>