def METHOD_NAME(self) -> Tuple[npt.ArrayLike, npt.ArrayLike]:
    """
    The lower and upper bounds of the optimisation parameters.
    Each set of bounds must be convertible to a numpy array of
    floats. If the lower or upper bound is a scalar value, that
    value is set as the bound for each of the optimisation
    parameters.
    """
    return -np.inf, np.inf