def post_config_hook(self):
        """
        Format of total, up and down placeholders under FORMAT.
        As default, substitutes left_align and precision as %s and %s
        Placeholders:
            value - value (float)
            unit - unit (string)
        """
        if not self.py3.check_commands("vnstat"):
            raise Exception(STRING_NOT_INSTALLED)
        elif self.statistics_type not in ["d", "m"]:
            raise Exception(STRING_INVALID_TYPE)
        self.slice = slice(*(3, 6) if self.statistics_type == "d" else (8, 11))
        self.value_format = "{{value:{}.{}f}} {{unit}}".format(self.left_align, self.precision)
        # list of units, first one - value/initial_multi, second - value/1024,
        # third - value/1024^2, etc...
        self.units = ["kb", "mb", "gb", "tb"]

        # deprecations
        self.coloring = getattr(self, "coloring", None)
        if self.coloring and not self.thresholds:
            self.thresholds = [(num * 1024**2, col) for num, col in self.coloring.items()]

        self.thresholds_init = self.py3.get_color_names_list(self.format)

        Format of total, up and down placeholders under FORMAT.
        As default, substitutes left_align and precision as %s and %s
        Placeholders:
            value - value (float)
            unit - unit (string)
        
py3status/modules/vnstat.py