100 – Filtering Truthy values

The built-in filter accepts the special value None as its first argument, instead of a predicate function. When None is the first argument, filter will remove all Falsy values from the iterable passed as the second argument.

words = ["This", "", None, "list", "contains", "", "some", "words"]

for word in filter(None, words):
    print(f"Word {word!r} has length {len(word)}.")

Word 'This' has length 4.
Word 'list' has length 4.
Word 'contains' has length 8.
Word 'some' has length 4.
Word 'words' has length 5.

In the snippet above, by using filter(None, ...), the loop skips over the empty strings "" in the list words and also the value None, since those are all Falsy.