def set_global_constants(normalize_damping_power=None, pi_type=None):
    """Sets various global constants used by the classes in this module."""
    global NORMALIZE_DAMPING_POWER
    global PI_TYPE
    if normalize_damping_power is not None:
        NORMALIZE_DAMPING_POWER = normalize_damping_power
    if pi_type is not None:
        PI_TYPE = pi_type
