def _augknt(x, k):
 return np.r_[(((x[0],) * k), x, ((x[(-1)],) * k))]

def _augknt ( x , k ) : return np . r_ [ ( ( ( x [ 0 ] , ) * k ) , x , ( ( x [ ( - 1 ) ] , ) * k ) ) ]
construct a knot vector appropriate for the order-k interpolation .