input: 
  from typing import List
  
  
  def is_armstrong_number(num: int) -> bool:
      """ Check if a given number is an Armstrong number.
      An Armstrong number is a number that is equal to the sum of its own digits
      each raised to the power of the number of digits.
      >>> is_armstrong_number(153)
      True
      >>> is_armstrong_number(9474)
      True
      >>> is_armstrong_number(12)
      False
      """
      digits = str(num)
      n = len(digits)
      sum_of_digits = sum(int(digit) ** n for digit in digits)
      return num == sum_of_digits
  
output:     digits = str(num)
      n = len(digits)
      sum_of_digits = sum(int(digit) ** n for digit in digits)
      return num == sum_of_digits