How to get a false-like value instead of error when retrieving non-existent elements in lists or dictionaries in Python

for a dictionary you can use a defaultdict from the collections module I.E:

from collections import defaultdict

my_dict = defaultdict(lambda: False)

my_dict['test']  # This will be False

You can read more about defaultdict in the docs

For a list however it gets a bit more complicated, sublcassing list and overriding the __getitem__ method to wrap the call in a try/except clause and return a different value:

class defaultlist(list):
    def __getitem__(self, key):
        try:
            return super().__getitem__(key)
        except IndexError:
            return False

my_list = defaultlist()
my_list[10]  # This will be False