Rest api expr w/ andX syntax

Your software
My Mautic version is: 4.0
My PHP version is: 7.4
My Database type and version is: tidb

Your problem

shows the expr syntax

I want to e.g. do a query from leads/contacts (via rest) where e.g. email is not null and company is null.

where[0][col]=email&where[0][expr]=isNotNull&where[1][col]=company&where[1][expr]=isNull

is an or.

I see an ‘andX’ operator, but, what is the syntax to use it? Where would it go in this expression?