title: Use connection pool with MongoEngine
body: <p>I have documents in different MongoDB databases referencing each other (mongoengine's LazyRefereneceField), so each time I need to get the field's value, I need to connect and disconnect from the field's relevant database, which I find very inefficient.</p>
  <p>I've read about connection pooling, but I can't find a solution on how to implement it using MongoEngine. How can I create a connection pool and reuse connections from it every time I need to the value for a LazyReferenceField?</p>