-----Description-----
This task requires writing a Lean 4 method that determines whether a given number `n` is an Armstrong number (also known as a Narcissistic number). An Armstrong number is a number that is equal to the sum of its own digits raised to the power of the number of digits.

-----Input-----
The input consists of one natural number:
- `n: Nat`: The number to check if it satisfies the Armstrong property.

-----Output-----
The output is a boolean value:
- `Bool`: Return `true` if `n` is an Armstrong number, otherwise return `false`.

