def METHOD_NAME(self: DeliveryGeneric, mask) -> DeliveryGeneric:
    cls = type(self)
    new_delivery_data = []
    for item in self:
        new_delivery_data.append(np.array(item)[mask])
    new_monitor_units = new_delivery_data[0]
    try:
        first_monitor_unit_item = new_monitor_units[0]
    except IndexError:
        return cls(*new_delivery_data)
    new_delivery_data[0] = np.round(
        np.array(new_delivery_data[0], copy=False) - first_monitor_unit_item,
        decimals=7,
    )
    return cls(*new_delivery_data)