def lookup_ancestors #:nodoc:
      klass = self
      classes = [klass]
      return classes if klass == ActiveRecord::Base

      while !klass.base_class?
        classes << klass = klass.superclass
      end
      classes
    end
def lookup_ancestors #:nodoc:
      klass = self
      classes = [klass]
      return classes if klass == ActiveRecord::Base

      while !klass.base_class?
        classes << klass = klass.superclass
      end
      classes
    end
Set the lookup ancestors for ActiveModel.