When you have a object `x`

and assign `y = x`

, `y`

will be a ref of `x`

(it looks like pointer of C). So changing property of `y`

means changing property of `x`

.

Ex :

`x = {"a": 1, "b": 2}`

y = x

y['a'] = 100

print x['a'] # Result is 100

So if you want clone the value, use `copy`

lib :

`import copy`

x = {"a": 1, "b": 2}

y = copy.deepcopy(x)

y['a'] = 100

print x['a'] # Result is 1