DigitalDemiurge/pikachu — pull request #2 by szuliq (2013-11-21 08:10:58+00:00)
Title: Stop initializing an argument with an empty list

The user needs to be very careful not to append anything to the lists if no subscriber/method was given. Otherwise the appended stuff will be class-wide accessible.

```python
class A(object):

def __init__(self, a=[]):
self.a = a

instance_1 = A()
instance_1.a # []
instance_1.a.append(1)

instance_2 = A()
instance_2.a # [1]
```