def isInstanceOrNone( obj, classType ):
    """
        Returns a boolean whether or not 'obj' is instanceof class
        'classType' (not as string, pass as real class!), or None.

        This function can be used for checking parameters that must be of a
        certain class, or are permitted to be None to e.g. fallback to the
        defaults.
    """
    return isinstance( obj, classType ) or obj is None