title: Merging 2 lists with linq based on unique Id to avoid duplicates
body: <p>I have two lists of products: products and extraProducts
  My goal is to merge the 2 lists but avoid duplicates based on the Id only.</p>
  
  <p><strong>Here is my best attempt:</strong></p>
  
  <pre><code>List&lt;Product&gt; allProductsWithNoDuplicates = new List&lt;Product&gt;();
  
  allProductsWithNoDuplicates.AddRange(products.Where(p =&gt; extraProducts.Select(ep =&gt; ep.Id).Contains(p.Id)).ToList());
  </code></pre>
  
  <p>However it does not work because it needs to be where NOT Contains.</p>