Behavior of statistics.mean

[DeaD_EyE]

In real world applications, you could use itertools.takewhile.
The itertools module is written in C, so it's faster than Python code.

from itertools import takewhile


def sum_user_input():

    def ask():
        while True:
            user_input = input("Enter a number: ")

            try:
                number = int(user_input)
            except ValueError:
                print(user_input, "is not a number")
                continue

            yield number

    return sum(takewhile(lambda x: x != 0, ask()))


result = sum_user_input()
print(result)