input: 
  def is_armstrong_number(num: int) -> bool:
      """ Check if a given number is an Armstrong number.
      An Armstrong number of n digits is an integer such that the sum of its 
      own digits each raised to the power of n is equal to the number itself.
      >>> is_armstrong_number(153)
      True
      >>> is_armstrong_number(9474)
      True
      >>> is_armstrong_number(123)
      False
      """
      n = len(str(num))
      sum_of_digits = sum(int(digit) ** n for digit in str(num))
      return num == sum_of_digits
  
output:     n = len(str(num))
      sum_of_digits = sum(int(digit) ** n for digit in str(num))
      return num == sum_of_digits