You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: utils_states.rs
    path of file: ./repos/deep_causality/deep_causality/examples/csm/src
    
    the code of the file until where you have to start completion: // SPDX-License-Identifier: MIT
// Copyright (c) "2023" . The DeepCausality Authors. All Rights Reserved.

use deep_causality::prelude::{
    BaseCausaloid, CausalityError, Causaloid, IdentificationValue, NumericalValue,
};

pub fn get_smoke_sensor_causaloid<'l>() -> Ba
    
fn verify_obs(obs: NumericalValue) -> Result<(), CausalityError> {
    if obs.is_nan() {
        return Err(CausalityError("Observation is NULL/NAN".into()));
    }

    if obs.is_infinite() {
        return Err(CausalityError("Observation is infinite".into()));
    }

    if obs.is_sign_negative() {
        return Err(CausalityError("Observation is negative".into()));
    }

    Ok(())
}