# File lib/ancestry/class_methods.rb, line 9
    def scope_depth depth_options, depth
      depth_options.inject(self.base_class) do |scope, option|
        scope_name, relative_depth = option
        if [:before_depth, :to_depth, :at_depth, :from_depth, :after_depth].include? scope_name
          scope.send scope_name, depth + relative_depth
        else
          raise Ancestry::AncestryException.new("Unknown depth option: #{scope_name}.")
        end
      end
    end