def zero(sys):
    """
    Compute system zeros.

    Parameters
    ----------
    sys: StateSpace or TransferFunction
        Linear system

    Returns
    -------
    zeros: ndarray
        Array that contains the system's zeros.

    Raises
    ------
    NotImplementedError
        when called on a MIMO system

    See Also
    --------
    pole
    StateSpace.zero
    TransferFunction.zero

    """
    return sys.zero()
