How to write predicate for column that has "or" in its name in ransack gem?

Question

How can I write a predicate for a column that has or in its name? For example, I have a column called education_secondary_or_less, and I want a predicate that will check whether the value is null, which I can write like this:

education_secondary_or_less_not_null

But I get an error when I write a predicate like that:

undefined method `education_secondary_or_less_not_null' for #<Ransack::Searc