<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def rskew_normal(mu, tau, alpha, size=()):
 """ Skew-normal random variates. """

    size_ = size or (1,)
    len_ = np.prod(size_)
    return flib.rskewnorm(
        len_, mu, tau, alpha, np.random.normal(size=2 * len_)).reshape(size)