I am trying to create the following query using knex:

`SELECT * FROM users group by users.location having users.photo is not null` 

as follows:

`knex("users").groupBy("users.location").having("users.photo", "IS NOT", "Null")`

I am getting the following error on this:

`The operator IS NOT is not permitted`

I've gone through their documentation and couldn't find anything useful.