class Ransack::Nodes::Condition

def arel_predicate_for_attribute(attr)
  if predicate.arel_predicate === Proc
    values = casted_values_for_attribute(attr)
    unless predicate.wants_array
      values = values.first
    end
    predicate.arel_predicate.call(values)
  else
    predicate.arel_predicate
  end
end