input: Write a python function to perform XOR operation on two strings and return the result in hexadecimal format.
  assert xor_strings("TestPassword", "TopSecret") == "000032051F0103000E05"
  assert xor_strings("hello", "world") == "1F051C0B1B"
  assert xor_strings("abc", "123") == "505152"
output: def xor_strings(s1, s2):
      result = ''.join(format(ord(a) ^ ord(b), '02X') for a, b in zip(s1, s2))
      return result