def set_discretized(cls, val=False):
        """Sets the `discretized` flag.

        Parameters
        ----------
        val : bool
            Flag identifying whether the features are discretized or not.
            Default is False.

        Raises
        ------
        ValueError
            If `val` is not boolean type.

        """
        if not isinstance(val, bool):
            raise ValueError("Attribute 'nfeatures' must be of <type 'bool'>, got %s" % str(type(val)))
        cls.discretized = val