<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _ppoints(n, a=0.5):
 """ Ordinates For Probability Plotting. Numpy analogue or `R`'s `ppoints` function. Parameters n : int Number of points generated a : float Offset fraction (typically between 0 and 1) Returns ------- p : array Sequence of probabilities at which to evaluate the inverse distribution. """

    a = 3 / 8 if n <= 10 else 0.5
    return (np.arange(n) + 1 - a) / (n + 1 - 2 * a)