title: Cloudformation nested stack outputs in yaml
body: <p>In my nested stacks I need to use output values and AWS::CloudFormation::Stack returns values as </p>
  
  <p>Fn::GetAtt
  Outputs.NestedStackOutputName</p>
  
  <p>But yaml doesn't allow me to use </p>
  
  <pre><code>!GetAtt MyResourceName.Outputs.MyOutputName
  </code></pre>
  
  <p>as it tries to split them into 3 pieces instead of the 2 it requires.</p>
  
  <p>I also tried using </p>
  
  <pre><code>Value: "Fn::GetAtt": [ "MyResourceName", "Outputs.MyOutputName" ] 
  </code></pre>
  
  <p>but then I get</p>
  
  <pre><code>mapping values are not allowed here
    in "&lt;string&gt;", line 21, column 24:
          Value: "Fn::GetAtt": [ "MyResourceName", "Outputs.MyOutputName" ]
  </code></pre>
  
  <p>So how am I supposed to use this? Do I really have to switch to json for this?</p>