title: Error in $gte aggregation expression: "Expression $gte takes exactly 2 arguments. 1 were passed in."
body: <p>I'm getting this error while trying </p>
  
  <pre><code>db.any.aggregate([
   {  "$project": { n: {$gte: 0}}    }
  ])
  </code></pre>
  
  <p>I'm sure must be something obvious, but I cannot find the error. Using mongo 3.4 from the shell client</p>