input: Write a function to edit a given Python program that prints 'Hello World' 10 times and modify it to print 'Happy Holidays' 10 times. The function should take the original program as a string and return the modified program as a string.
  assert modify_program("for i in range(10):\n    print('Hello World')")=="for i in range(10):\n    print('Happy Holidays')"
output: def modify_program(program):
      return program.replace("Hello World", "Happy Holidays")