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. If the given number is an Armstrong number return True else return False. The function should handle both positive and negative numbers, returning False for negative inputs.
  def is_armstrong_number(num):
      if num < 0:
          return 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
  
  assert is_armstrong_number(153)==True
  assert is_armstrong_number(9474)==True
  assert is_armstrong_number(123)==False
  assert is_armstrong_number(9475)==False
  assert is_armstrong_number(-153)==False
output: def is_armstrong_number(num):
      if num < 0:
          return 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