title: MongoDB return True if document exists
body: <p>I want to return true if a userID already exists and false otherwise from my collection.I have this function but it always returns <code>True</code>.</p>
  
  <pre><code>def alreadyExists(newID):
      if db.mycollection.find({'UserIDS': { "$in": newID}}):
          return True
      else:
          return False
  </code></pre>
  
  <p>How could I get this function to only return true if a user id already exists?</p>