creates example data set

def make_data():
    """creates example data set"""
    n = 30      # number of stages
    z = 1.65    # for 95% service level
    sigma = 100 # demand's standard deviation
    h = {}      # inventory cost
    T = {}      # production lead time
    h[n] = 1
    for i in range(n-1,0,-1):
        h[i] = h[i+1] + random.randint(30,50)
    K = 0 # number of segments (=sum of processing times)
    for i in range(1,n+1):
        T[i] = random.randint(3,5)      # production lead time at stage i
        K += T[i]
    return z,sigma,h,T,K,n