def _flux_rate(model, subcatchment, lid_index, layer):
    """
    Get lid net inflow - outflow from previous time step for each lid layer
    ONLY FOR for surface, soil, storage, pave
    :param int layerIndex: layer type (toolkitapi.LidLayers member variable)
    :return: Parameter Value
    :rtype: double
    """
    return model.getLidUFluxRates(subcatchment, lid_index, layer)
