input: from typing import List
  
  def is_armstrong_number(num: int) -> bool:
      """ Check if a given number is an Armstrong number.
      >>> is_armstrong_number(153)
      True
      >>> is_armstrong_number(9474)
      True
      >>> is_armstrong_number(123)
      False
      """
      n = len(str(num))  
      temp = num  
      sum_of_digits = 0
    
      while temp > 0:  
          digit = temp % 10  
          sum_of_digits += digit ** n  
          temp //= 10  
    
      if num == sum_of_digits:  
          return True  
      else:  
          return False
output:     n = len(str(num))  
      temp = num  
      sum_of_digits = 0
    
      while temp > 0:  
          digit = temp % 10  
          sum_of_digits += digit ** n  
          temp //= 10  
    
      if num == sum_of_digits:  
          return True  
      else:  
          return False