input: Write a function to modify a given Python program to print 'Happy Holidays' 10 times. The original program prints 'Hello World' 10 times. Return the modified program as a string. If the input program is not in the expected format, return an error message.
  assert modify_program("for i in range(10):\n    print('Hello World')")=="for i in range(10):\n    print('Happy Holidays')"
  assert modify_program("for i in range(5):\n    print('Hello World')")=="Invalid format: The program does not contain the expected print statement for 'Hello World' 10 times."
  assert modify_program("")=="Invalid format: The input program is empty."
  assert modify_program("print('Hello World')")=="Invalid format: The program does not contain the expected print statement for 'Hello World' 10 times."
  assert modify_program("for i in range(10):\n    print('Hello Holidays')")=="Invalid format: The program does not contain the expected print statement for 'Hello World' 10 times."
output: def modify_program(program):
      if not program:
          return "Invalid format: The input program is empty."
      if "for i in range(10):\n    print('Hello World')" not in program:
          return "Invalid format: The program does not contain the expected print statement for 'Hello World' 10 times."
      return program.replace("Hello World", "Happy Holidays")