Node data history period

[Alfy102]

Hi, I just want some clarification on what input can I use when using the period for historize data change. For example if I want to store history for the last hour only, would that mean I have to input period=timedelta(hours=1)? Would the 1 hour be counted right after the server started? or is it hourly like 1PM, 2PM, 3PM...or so on?

async def historize_node_data_change(self, node, period=timedelta(days=7), count=0):
        """
        Start historizing supplied nodes; see history module
        :param node: node or list of nodes that can be historized (variables/properties)
        :param period: time delta to store the history; older data will be deleted from the storage
        :param count: number of changes to store in the history
        """

Thanks in advance.