title: c# Lambda query in list that has a list inside for mapping
body: <p>Today I'm mapping my objects to DTO like this.</p>
  
  <pre><code>public IEnumerable&lt;ArticleDTO&gt; GetArticlesBasedOnCategorySection(int catSection, int headCategoryID, string customerREFID)
  {
      return _articleRepository.GetArticlesByCategory(catSection, headCategoryID, customerREFID).Select(a =&gt; Mapper.ToDTO(a)).ToList();
  }
  </code></pre>
  
  <p>But inside the variable I have another list that I want to map in a similar way.
  Is it possible to write this all in one line like this or do I have to write an <code>foreach</code> loop then map a.List.</p>