Cannot update dictionary - python-3.8

Question

I have a dict_ class that attempts to copy the built-in dict class.
Here is that class (the new function returns the original object):
class dict_:
def __init__(self, *args, **kwargs):
self.kv = kwargs
if not self.kv:
for kv in args:
for k, v in kv:
self.kv.update({k: v})
def __str__(self):
return "%s" % self.kv
def __getitem__(self, item):
return self.kv[item]
def update(self, *args):
self.kv.update(args)
I've called it like this:
from Dodger.dodger import *
term = new(System())
a = new(dict_(a=1, b=2))
a.update(new(dict_(c=3)))
term.println(a)
This is supposed to modify a to {"a": 1, "b": 2, "c": 3} but instead it gives me this error:
Traceback (most recent call last):
File "C:/free_time/Dodger/dodger_test.py", line 5, in <module>
File "C:\free_time\Dodger\dodger.py", line 176, in update
File "C:\free_time\Dodger\dodger.py", line 173, in __getitem__
KeyError: 0
Why is it giving a KeyError? What does the 0 mean? (I am using python 3.8.2)

Answer 1

I figured out how to solve this problem. I just have to implement __setitem__ too:
def __setitem__(self, key, value):
"""Set self[key] to value"""
self.kv[key] = value