input: Write a function to check if a given string contains the word "Hello". If it contains the word "Hello", return True, otherwise return False.
  def check_hello(s):
      return 'Hello' in s
  assert check_hello("Hello, how are you?")==True
  assert check_hello("Goodbye, see you later")==False
  assert check_hello("Hello")==True
  assert check_hello("")==False
  assert check_hello("HELLO world")==False
output: def check_hello(s):
      return 'Hello' in s