# File lib/symetrie_com/acts_as_better_nested_set.rb, line 480
        def roots(scope = {})
          self.class.find_in_nested_set(:all, { :conditions => "#{scope_condition} AND (#{prefixed_parent_col_name} IS NULL OR #{prefixed_parent_col_name} = 0)", :order => "#{prefixed_left_col_name}" }, scope)
        end