How to use the pyodesys.util._Blessed function in pyodesys

def _ensure_4args(func):
    """ Conditionally wrap function to ensure 4 input arguments

    Parameters
    ----------
    func: callable
        with two, three or four positional arguments

    Returns
    -------
    callable which possibly ignores 0, 1 or 2 positional arguments

    """
    if func is None:
        return None
    if isinstance(func, _Blessed):  # inspect on __call__ is a hassle...
        return func

    self_arg = 1 if inspect.ismethod(func) else 0
    if hasattr(inspect, 'getfullargspec'):
        args = inspect.getfullargspec(func)[0]
    else:  # Python 2:
        args = inspect.getargspec(func)[0]
    if len(args) == 4 + self_arg:
        return func
    if len(args) == 3 + self_arg:
        return lambda x, y, p=(), backend=math: func(x, y, p)
    elif len(args) == 2 + self_arg:
        return lambda x, y, p=(), backend=math: func(x, y)
    else:
        raise ValueError("Incorrect numer of arguments")

return lambda x, y, p=(), backend=math: func(x, y, p)
    elif len(args) == 2 + self_arg:
        return lambda x, y, p=(), backend=math: func(x, y)
    else:
        raise ValueError("Incorrect numer of arguments")


def _default(arg, default):
    return default if arg is None else arg


def _concat(*args):
    return np.concatenate(list(map(np.atleast_1d, args)))


class _Callback(_Blessed):

    def __init__(self, indep, dep, params, exprs, Lambdify=None):
        self.indep, self.dep, self.params = indep, dep, params
        if indep is None:
            self.args = _concat(self.dep, self.params)
        else:
            self.args = _concat(self.indep, self.dep, self.params)
        self.input_width = len(self.args)
        self.exprs = exprs
        self.callback = Lambdify(self.args, self.exprs)
        self.ny = len(dep)
        self.take_params = len(params)

    def __call__(self, x, y, params=(), backend=None):
        _x = np.asarray(x)
        _y = np.asarray(y)