input: Write a function to add two large numbers represented as strings. The function should return the sum as a string, ensuring that carry and digit management are handled correctly. If either of the input strings is empty, the function should return the non-empty string or "0" if both are empty.
  def add_large_numbers(num1, num2):
      if not num1:
          return num2 or "0"
      if not num2:
          return num1 or "0"
  
      num1 = num1[::-1]
      num2 = num2[::-1]
      carry = 0
      result = ""
  
      for i in range(max(len(num1), len(num2))):
          digit1 = int(num1[i]) if i < len(num1) else 0
          digit2 = int(num2[i]) if i < len(num2) else 0
  
          sum_total = digit1 + digit2 + carry
          carry = sum_total // 10
  
          result += str(sum_total % 10)
  
      if carry > 0:
          result += str(carry)
  
      return result[::-1]
  
  assert add_large_numbers("111", "1337")=="1448"
  assert add_large_numbers("12345678901234567890", "98765432109876543210")=="111111111011111111100"
  assert add_large_numbers("456", "")=="456"
  assert add_large_numbers("", "123")=="123"
  assert add_large_numbers("", "")=="0"
output: def add_large_numbers(num1, num2):
      if not num1:
          return num2 or "0"
      if not num2:
          return num1 or "0"
  
      num1 = num1[::-1]
      num2 = num2[::-1]
      carry = 0
      result = ""
  
      for i in range(max(len(num1), len(num2))):
          digit1 = int(num1[i]) if i < len(num1) else 0
          digit2 = int(num2[i]) if i < len(num2) else 0
  
          sum_total = digit1 + digit2 + carry
          carry = sum_total // 10
  
          result += str(sum_total % 10)
  
      if carry > 0:
          result += str(carry)
  
      return result[::-1]