title: JmesPath find where not exists
body: <p>The following JmesPath expression finds instances that have been tagged with a team:</p>
  
  <pre><code>"Instances[?Tags[?Key=='team']]"
  </code></pre>
  
  <p>Do you know how to find instances that are not tagged with a team?</p>
  
  <p>I have tried:</p>
  
  <pre><code>"Instances[?!Tags[?Key=='team']]"
  -&gt; !Tags[?Key=='team']]: event not found
  "Instances[?null==Tags[?Key=='team']]"
  -&gt; []  &lt;-- wrong answer
  "Instances[?!not_null(Tags[?Key=='team'])]"
  -&gt; !not_null: event not found
  </code></pre>
  
  <p>Many thanks in advance!</p>
  
  <p>Sample input:</p>
  
  <pre><code>{ "Instances":
    [ { "id": "i-911"
      , "Tags":
        [ {"Key":"owner", "Value":"Edu"}
        , {"Key":"team", "Value":"forensics"}
        ]
      , "many other keys": "stuff"
      }
    , { "id": "i-999"
      , "Tags":
        [ {"Key":"owner", "Value":"Edu"}
        , {"Key":"note", "Value":"No team!"}
        ]
      , "many other keys": "stuff"
      }
    ]
  }
  </code></pre>