def page(num, opts = {})
      per_page = opts[:per_page].to_i || 20
      start  = per_page * (num - 1)
      self.class.new(@backend, @initial_key, @associated_class,
        @callback_target_class, @callback_target_id, @callbacks, @sort_order,
        self, ::Zermelo::Filters::Steps::ListStep.new({:offset => start,
          :limit => per_page}, {}))
    end
def page(num, opts = {})
      per_page = opts[:per_page].to_i || 20
      start  = per_page * (num - 1)
      self.class.new(@backend, @initial_key, @associated_class,
        @callback_target_class, @callback_target_id, @callbacks, @sort_order,
        self, ::Zermelo::Filters::Steps::ListStep.new({:offset => start,
          :limit => per_page}, {}))
    end
(a different syntax to the above)