input: Write a function to determine if a given string contains the word "Hello". If it contains the word "Hello", return True; otherwise, return False. The function should be case-sensitive.
  def check_hello(s):
      return 'Hello' in s
  assert check_hello("Hello world")==True
  assert check_hello("helloworld")==False
  assert check_hello("Hello123")==True
  assert check_hello("Hi there")==False
  assert check_hello("")==False
output: def check_hello(s):
      return 'Hello' in s