title: Linq Aggregate complex types into a string
body: <p>I've seen the simple example of the .net Aggregate function working like so:</p>
  
  <pre><code>string[] words = { "one", "two", "three" };
  var res = words.Aggregate((current, next) =&gt; current + ", " + next);
  Console.WriteLine(res);
  </code></pre>
  
  <p>How could the 'Aggregate' function be used if you wish to aggregate more complex types?
  For example: a class with 2 properties such as 'key' and 'value' and you want the output like this: </p>
  
  <pre><code>"MyAge: 33, MyHeight: 1.75, MyWeight:90"
  </code></pre>