def cubic_spline(x, y):
    n = len(x)
    h = [x[i+1] - x[i] for i in range(n-1)]
    alpha = [3*(y[i+1] - y[i])/h[i] - 3*(y[i] - y[i-1])/h[i-1] for i in range(1, n-1)]

abc
def