def TransferFunction(num:list[float], den:list[float], deadtime: float = 0.0, dt:float=0.0) -> control.TransferFunction:
    """
    Creates a discrete-time transfer function with the given numerator and 
    denominator coefficients.
    Also adds deadtime to the transfer function if given.

    Parameters
    ----------
    num : list
        Numerator coefficients of the transfer function
    den : list
        Denominator coefficients of the transfer function
    deadtime : float, optional
        Deadtime of the transfer function, by default 0
    dt : float, optional
        Sampling time of the transfer function, by default 0.1
    
    Returns
    -------
    control.TransferFunction
        Discrete-time transfer function with the given parameters
    
    Examples
    --------
    >>> import matplotlib.pyplot as plt
    >>> num = [0.9958683]
    >>> den = [1, -0.0041317]
    >>> deadtime = 5
    >>> dt = 0.5
    >>> Gz = TransferFunction(num, den, deadtime, dt)
    >>> print(Gz.dcgain)
    >>> y, t = Gz.step_response
    >>> plt.title('Stepresponse (Y per U)')
    >>> plt.plot(t, y, '-r')
    >>> plt.xlabel('Time(min)')
    >>> plt.ylabel('Amplitude')
    >>> plt.grid()
    >>> plt.show()
    """
    if dt:
        Gz = control.TransferFunction(num, den, dt)
    else:
        Gs = control.TransferFunction(num, den)
        # dt = get_dt(Gs)
        dt = 0.1
        Gz = control.sample_system(Gs, dt, 'tustin')
    if deadtime >= 1:
        deadtime_samples = int(np.ceil(deadtime/dt)) + 1
        theta = np.full(deadtime_samples, 0.0)
        for i in range(len(theta)):
            if i % 2 != 0:
                theta[i] = -0.0
        denz = np.concatenate((Gz.den[0][0].flatten(), theta), axis=None)
        Gz.den[0][0] = denz
    return Gz