title: Total sum for an object property value in a list using a lambda function
body: <p>I have the following: <code>List&lt;OutputRow&gt;</code> which contains a number of <code>OutputRow</code> objects.</p>
  
  <p>I am wondering if there is a way for me to use a lambda function on the list to return the total sum of the values of a certain propertyX on each OutputRow object in the list. </p>
  
  <p>Example list:</p>
  
  <pre><code>OutputRow.propertyX = 4  
  OutputRow.propertyX = 6  
  OutputRow.propertyX = 5  
  </code></pre>
  
  <p>return 15 </p>