empty dictionary as default value for keyword argument in python function: dictionary seems to not be initialised to {} on subsequent calls? [duplicate]

Answer 1

>>> def f(i, d=None, x=3):
...     if not d:
...         d={}
...     d[i] = i*i
...     x += i
...     return x,d
... 
>>> f(2)
(5, {2: 4})
>>> f(3)
(6, {3: 9})
>>>