@classmethod
def getInitialDisplayRange(cls):
    """This class method returns a tuple containing ``(low, high)``
        percentile values which are used to set the initial values for the
        :attr:`.ColourMapOpts.displayRange` and
        :attr:`.ColourMapOpts.clippingRange` properties. If the initial
        display range has not yet been set (via the
        :meth:`setInitialDisplayRange` method), ``None`` is returned.
        """
    try:
        return cls.__initialDisplayRange
    except AttributeError:
        return None
