Custom Native operator is not recognized

[vctls]

It may be a duplicate of #40 .
I'm trying to create an "isnull" operator with two implementations, to be used on objects and query builders.
But the native rule doesn't even get to the compile part. It fails in the Llk/Parser.php
Unexpected token "isnull" (identifier)

Is it even possible to create custom native operators?

[vctls]

Ok, it works with the syntax isnull(object_or_property).
I'm not sure I fully understand the grammar, but I suppose the parser expects a specific syntax for an operation that only takes one parameter.
Sadly, Doctrine doesn't allow comparison with null on associations, so isnull(association) throws a Semantical Error.