# #TIL : Reference assign object variable

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
```