["python","dictionary"]
How to create key or append an element to key?

I have an empty dictionary. Name: dict_x It is to have keys of which values are lists. From a separate iteration, I obtain a key (ex: key_123), and an item (a tuple) to place in the list of dict_x's value key_123. If this key already exists, I want to append this item. If this key does not exist, I want to create it with an empty list and then append to it or just create it with a tuple in it. In future when again this key comes up, since it exists, I want the value to be appended again. My code consists of this: Get key and value. See if NOT key exists in dict_x. and if not create it: dict_x[key] == [] Afterwards: dict_x[key].append(value) Is this the way to do it? Shall I try to use try/except blocks?
Use dict.setdefault(): dict.setdefault(key,[]).append(value) help(dict.setdefault): setdefault(...) D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D