def max_age(self, max_age):
        """Sets the max_age of this Params.

        Maximum age (in hours) for the repo to be considered.
        Any repo tested or being tested after \"now - max_age\" will be taken
        into account. If set to 0, all repos will be considered.

        :param max_age: The max_age of this Params.
        :type: int
        """
        if max_age is None:
            raise ValueError("Invalid value for `max_age`, must not be `None`")
        if max_age is not None and max_age < 0:
            raise ValueError("Invalid value for `max_age`, must be a value"
                             " greater than or equal to `0`")

        self._max_age = max_age