title: erb if conditions with environment variables
body: <p>I'm trying to do something like this for a sinatra app using erb.  I've been struggling with it for quite a while and have had trouble finding good documentation for erb.  Any thoughts on how to implement a working version of this would be very much appreciated.</p>
  
  <pre><code>&lt;% if employee['filename'] == nil %&gt;
                  &lt;img width="70" height="70" src="#{ENV['no_image_url']}"&gt;
                  &lt;% else %&gt;
                  &lt;img width="70" height="70" data-src="#{ENV['employee_image']" src="#{ENV['employee_image']"&gt;
                  end
  </code></pre>