python random get the same result when using in a for loop

Question

I am quite confused with the output with the following codes, where I wanted to initialize the 10 range clusters with random numbers. However, the results are all the same.

import random
class range_cluster:
    def __init__(self,ranges=[]):
        self.ranges = ranges

def generate_range_cluster(nclusters):
    range_clusters = [range_cluster() for _ in xrange(nclusters)]
    for rc in range_clusters:
        rc.ranges.append([random.random(),random.random()])
    return range_clusters

def main():
    nclusters = 10
    range_clusters = generate_range_cluster(nclusters)
    for rc in range_clusters:
        print rc.ranges[0][0],rc.ranges[0][1]

main()

results:

0.60436009302 0.361964915468
0.60436009302 0.361964915468
0.60436009302 0.361964915468
0.60436009302 0.361964915468
0.60436009302 0.361964915468
0.60436009302 0.361964915468
0.60436009302 0.361964915468
0.60436009302 0.361964915468
0.60436009302 0.361964915468
0.60436009302 0.361964915468