python append value to dictionary list

import collections

a_dict = collections.defaultdict(list) # a dictionary key --> list (of any stuff)
a_dict["a"].append("hello")

print(a_dict)
>>> defaultdict(, {'a': ['hello']})

a_dict["a"].append("kite")

print(a_dict)
>>> defaultdict(, {'a': ['hello', 'kite']})

Here is what the above code is Doing:
1. Create a dictionary with default value as list.
2. Append “hello” to the list of key “a”.
3. Append “kite” to the list of key “a”.