Armstrong Number Python Solution with Tests

lcpy gen -n 1134   # by problem number
lcpy gen -s armstrong_number   # by problem name

Input: n = 153
Output: true
Explanation: 153 is a 3-digit number, and 153 = 1^3 + 5^3 + 3^3.

Input: n = 123
Output: false
Explanation: 123 is a 3-digit number, and 123 != 1^3 + 2^3 + 3^3 = 36.

class Solution:
    # Time: O(log n)
    # Space: O(1)
    def is_armstrong(self, n: int) -> bool:
        digits = str(n)
        k = len(digits)
        return sum(int(d) ** k for d in digits) == n