input: Write a function to determine if two integers are equal. If they are equal, return a message saying "The two integers are equal", otherwise return "The two integers are not equal". If either integer is not provided, return "Invalid input". 
  
  assert check_equal_integers(10, 10)=="The two integers are equal"
  assert check_equal_integers(5, 7)=="The two integers are not equal"
  assert check_equal_integers(0, 0)=="The two integers are equal"
  assert check_equal_integers(None, 2)=="Invalid input"
  assert check_equal_integers(3, None)=="Invalid input"
  assert check_equal_integers(None, None)=="Invalid input"
output: def check_equal_integers(a, b):
      if a is None or b is None:
          return "Invalid input"
      if a == b:
          return "The two integers are equal"
      else:
          return "The two integers are not equal"