Armstrong Number Check

An **Armstrong number** (also called a **narcissistic number**) is an integer that is equal to the sum of its own digits each raised to the power of the number of digits. For example: - 153 has 3 digits: 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153 → true - 1634 has 4 digits: 1^4 + 6^4 + 3^4 + 4^4 = 1 + 1296 + 81 + 256 = 1634 → true - 123 has 3 digits: 1^3 + 2^3 + 3^3 = 36 ≠ 123 → false Define a function `is_armstrong(n: int) -> bool` that returns `True` if `n` is an Armstrong number, and `False` otherwise. The input `n` is a non-negative integer. For `n = 0`, the function should return `True` (a single digit 0 to the power 1 equals 0).

>>> is_armstrong(153)
True
>>> is_armstrong(123)
False
>>> is_armstrong(0)
True