input: Write a function to check if a given number is an Armstrong number. An Armstrong number (also known as a narcissistic number) is a number that is the sum of its own digits each raised to the power of the number of digits. The function should return True if the number is an Armstrong number, otherwise it should return False. If the input number is less than 0, the function should return False.
  def is_armstrong_number(num):
    if num < 0:
      return False
    order = len(str(num))
    sum = 0
    temp = num
    while temp > 0:
      digit = temp % 10
      sum += digit ** order
      temp //= 10
    return num == sum
  assert is_armstrong_number(153)==True
  assert is_armstrong_number(9474)==True
  assert is_armstrong_number(123)==False
  assert is_armstrong_number(54748)==True
  assert is_armstrong_number(-54748)==False
output: def is_armstrong_number(num):
    if num < 0:
      return False
    order = len(str(num))
    sum = 0
    temp = num
    while temp > 0:
      digit = temp % 10
      sum += digit ** order
      temp //= 10
    return num == sum