title: LINQ: Select a collection?
body: <p>I'm trying to use LINQ:</p>
  
  <pre><code>IEnumerable&lt;String&gt; debtors = (from expense in CurrentExpenses
                                 where expense.WhoPaid == username
                                 select expense.WhoOwes.AsEnumerable()).Distinct();
  </code></pre>
  
  <p>(<code>username</code> and <code>WhoPaid</code> are strings, <code>WhoOwes</code> is <code>ICollection&lt;String&gt;</code>)</p>
  
  <p>What I want to do is get an <code>IEnumerable</code> of, for each <code>expense</code> where <code>username</code> paid, all the people who owe for it. I'm not really sure how to do it. Here is the compiler error:</p>
  
  <pre><code>Cannot implicitly convert type 'System.Collections.Generic.IEnumerable&lt;System.Collections.Generic.IEnumerable&lt;string&gt;&gt;' to 'System.Collections.Generic.IEnumerable&lt;string&gt;'. An explicit conversion exists (are you missing a cast?)
  </code></pre>
  
  <p>What is the correct syntax for this?</p>