defaultdict check if key exists

dct.get(key, 'ham')  # will return dct[key] or 'ham' but never stores anything

'in' is the intended way to test for the existence of a key in a dict.

d = {"key1": 10, "key2": 23}

if "key1" in d:
    print("this will execute")

if "nonexistent key" in d:
    print("this will not")