Support for lookup and graphLookup

[arichiardi]

Hi there!

I have been playing a bit around and I noticed that the $lookup and $graphLookup are not currently supported so I opened an issue for tracking it and to ask if there is a way, as a workaround, to use them by any chance.

Thanks for the project, I was able to get up and running in no time!

[arichiardi]

I found that I can use a simple "$graphLookup" instead of an operator.