def seq (): var n, x1, x2, x3, r x1 = n while x1 > 0: r = unif(-2,1) x1 = x1 + r tick 1 x2 = n while x2 > 0: r = unif(-2,1) x2 = x2 + r tick 1 x3 = n while x3 > 0: r = unif(-2,1) x3 = x3 + r tick 1