def intercept_signal(signal, start, stop=None, sf=128):
    """Intercept the required signal

    Parameters
    ----------
    signal : ndarray
        Target data, only the last dimension will be operated.

    start : int
        Start of interval. If stop is not given, start defaults to 0.

    stop : int
        End of interval.

    sf : int, default=128
        Sampling frequency of signal.

    Return
    ---------
    data : ndarray
    """
    if stop is None:
        start, stop = 0, start

    point_of_start, point_of_end = start*sf, stop*sf

    return signal[..., point_of_start:point_of_end]